Midi clock bug report Windows 11

Naor_Hazan · August 6, 2026, 9:07am

Hi Steinberg team

we have an issue with Cubase 15 on Windows 11 related to MIDI Clock Out after the recent Windows update. (i think they changed something with how midi works within windows and that got cubase unstable when sending midi clock out)

I was experiencing GUI freezes / hangs in Cubase 15. The computer itself remained responsive, but Cubase would still play the audio from that point on but the GUI will freeze . also midi (non freezed) instruments are not responsing and getting lost while this happends (the drums in my example). im attaching a youtube unlisted link for you to see the issue. After troubleshooting, I found that the issue was caused by Cubase constantly sending MIDI Clock out.

freeze start at 0:12
after it froze i tried clicking everywhere and nothing responded
in task manager it didnt say (nor responsive)

Once I disabled MIDI Clock Out in Cubase, the freezes stopped.

Steps to reproduce:

1. Open Cubase 15 on Windows 11.

2. Open a project.

3. Select an external MIDI destination or MIDI port as the MIDI Clock output. (Transport > Project Synchronization Setup>Destinations> (i used usb midi keyboard that midi out was connected to guitar pedals for midi clock bpm and start stop commands)

4. Work in the project for a while, it dosent happends immidiately.

5. Cubase GUI will freeze for a bit then update then freeze again and so on.

6. Disable MIDI Clock Out.

7. The issue no longer occurs.

Expected result:

Cubase should be able to send MIDI Clock Out continuously without the GUI freezing or the application becoming unresponsive.

Actual result:

Cubase becomes unresponsive / freezes while MIDI Clock Out is enabled. Disabling MIDI Clock Out stops the freezes.

System information:

Cubase version:

Cubase Pro 15.0.30

Operating system:

Windows 11 latest updates ( this is what triggered the whole issue)

Audio interface:

Apollo Twin X Gen1

MIDI devices / clock destinations:

Komplete Kontrol S61 MK3

GPU:

RTX 5070

Third-party MIDI tools / Virtual MIDI ports:

no virtual midi loopback is installed on my system - only midi device is the Komplete Kontrol MK3

Notes:

This does not seem to be related to CPU, RAM, GPU load, or plug-ins in my case. The problem appears specifically when Cubase is continuously sending MIDI Clock Out after the recent Windows 11 MIDI changes/update.

Psychlist1972 · August 6, 2026, 3:07pm

Can you go into Device Manager (right-click the Windows logo on the task bar, choose “Device Manager”), then scroll down to “Sound, video and game controllers”. Inside that section, find the Komplete Kontrol, right-click it, and choose “Properties”.

Then please paste in a screenshot of the first tab in the properties. This tab:

There is a known bug with the wrong type of framing for real-time messages if using our new driver. The screenshot you post will help me see if you are using that driver (which has the bug, but also supports the MK3’s MIDI 2.0 mode) or the older one (which doesn’t have the bug, but only supports the MK3’s MIDI 1.0 mode).

But in either case, I’m surprised that caused any sort of odd behavior in Cubase.

Thanks.

Pete
Microsoft

Naor_Hazan · August 6, 2026, 3:10pm

hey Pete!
here is the screenshot

@Psychlist1972

Psychlist1972 · August 6, 2026, 3:23pm

Ok, Yes. That is using the new driver instead of the old.

I don’t have a web article up for this yet, so for a walkthrough on how to switch between drivers (assuming the Kontrol is not in MIDI 2.0 mode), you’ll need to join the MIDI DIscord server here Windows MIDI / Audio . Once you join with that link, the instructions are in the #workarounds-and-instructions channel.

Pete
Microsoft

Psychlist1972 · August 7, 2026, 12:48am

I now have the web article up, so you don’t need to join Discord unless you want to

Pete
Microsoft

Naor_Hazan · August 7, 2026, 5:40am

thank you pete!
ive tried the mothod you suggested and it seems to work
but as you said, this is a workaround, not a solution.
because even though it works

im forced to use midi 1.0 instead of 2.0 (no big deal for me but its a limitation worth mentioning)
this is the situation by default so this issue probably happends to more people that have no idea why cubase is freezing for them

is there a solution on the works from microsoft side? or is there anything steinberg could do on thier side to fix it?

thank you for the fast reply!
@Psychlist1972

Psychlist1972 · August 7, 2026, 4:35pm

The driver bug will be fixed. Our next set of releases go out in November. I don’t know yet if this will be part of it.

Do you have the Kontrol in MIDI 2.0 mode? I thought it was just using MIDI 1.

To the best of my knowledge, if you switch the Kontrol over to MIDI 2.0 mode, this won’t be an issue. The Code Index Number bug is specific to MIDI 1 data format devices using the new combined MIDI 1.0/MIDI 2.0 class driver.

github.com/microsoft/MIDI

[BUG]: Code Index Number for System Realtime Messages in USB MIDI Packet seems to be wrong when using USBMidi2-ACX

opened 07:50AM - 04 Jun 26 UTC

tosugawara

bug

area-usb-driver

### Report pre-requisites - [x] I have searched this repo for existing issues t…o confirm this is not a duplicate - [x] I agree to follow this project's Code of Conduct ### Clarity and Disclosure - [x] I confirm that any AI analysis included in this report is clearly called out / tagged as AI-generated with "AI Generated Content". Reports with suspected AI content may be closed if not disclosed. - [x] I confirm that I will quickly follow-up to questions or requests for additional detail, otherwise the issue may be closed ### Windows Version Windows 11 Pro 25H2 26200.8524 ### Type of bug - [ ] Windows doesn't recognize MIDI device (doesn't show in device manager) - [ ] Application doesn't recognize MIDI device or ports - [ ] Cannot update firmware on MIDI device (specify device, app, and firmware info) - [x] MIDI device is recognized, but cannot send or receive messages - [ ] Sent or received MIDI messages are corrupted - [ ] Application not working as expected - [ ] MIDI 1.0 ports not named as expected - [x] Performance not as expected - [ ] Localization issue (incorrect or missing language for Windows running something other than en-US) - [ ] General application crash or hang - [ ] MIDI Service crash or hang requiring Windows reboot - [ ] Windows bugcheck / BSOD (please include in the areas below the device id from Windows Settings About page or a link to your crash dump uploaded to a sharing service) - [ ] Other or Unsure (please indicate in additional notes section below) ### Location - [x] Application using WinMM MIDI 1.0 (Classic API). Name provided below. - [ ] Application using WinRT MIDI 1.0 (Windows 10 MIDI). Name provided below. - [ ] Application using Windows MIDI Services SDK (MIDI 2.0). Name provided below. - [ ] Other app/DAW/tool. Not sure about which API or SDK it uses. Name provided below. - [ ] Windows MIDI Services tools like MIDI Settings, Console, etc. - [ ] Directly in Windows MIDI Services SDK (for Developers only, please provide repro code) - [ ] General Windows shell (Device Manager, Settings, Services, etc.). Name provided below. - [x] Windows MIDI 2.0 Class Driver (usbmidi2-acx) - [ ] Windows MIDI 1.0 Class Driver (usbaudio) - [ ] Vendor-provided MIDI driver (please provide details below) - [ ] Other or Unsure (please indicate in additional notes section below) ### Application Name and Version Pocket MIDI 64bit ### MIDI Device Name KORG nanoKEY Studio ### Output from the MIDI Diagnostics Tool [tmplz4zek.tmp.txt](https://github.com/user-attachments/files/28585912/tmplz4zek.tmp.txt) ### Repro - [x] I confirm that I was able to reproduce this issue using a simple app like `midi.exe`, `midi1monitor.exe` or `Pocket MIDI` - [ ] I tried but was unable to reproduce this issue using a simple application ### Steps to reproduce When WinMM app sends System Realtime Messages like Timing Clock (F8) to a MIDI 1.0 device installed Windows MIDI 2.0 Class Driver (usbmidi2-acx), Code Index Number of USB MIDI packets including the sent message is "0x5", which is for 1-Byte System Common Messages or the end of System Realtime Messages. This is supposed that "0xF" is originally correct for System Realtime Messages. When using MIDI 1.0 Class Driver, this seems to be "0xF". 1. Connect a MIDI 1.0 device to PC. (using KORG nanoKEY Studio here) 2. Confirm that Windows MIDI 2.0 Class Driver is installed to the device. 3. Launch Pocket MIDI and set MIDI IN/OUT port of the device. 4. Open Views > Timing Clock and click play button to transmit F8 messages. 5. Capture these messages by analyzer, the first byte of the USB MIDI Packet including a F8 message is "0x05".(see below) <img width="1077" height="614" alt="Image" src="https://github.com/user-attachments/assets/69e6758e-4fa3-4382-9aff-ed994de06f6c" /> 6. Replace the installed driver to Windows MIDI 1.0 Class Driver. 7. Do the same steps as 3-5, the first byte is "0x0F". (see below) <img width="1086" height="611" alt="Image" src="https://github.com/user-attachments/assets/c7f9e3c4-ff42-4cf5-8848-9516ee17a085" /> As a result, KORG nanoKEY Studio cannot correctly recognize System Realtime Messages (FA: Play, FC: Stop, and F8: Timing Clock) when using usbmidi2-acx. ### Expected behavior Code Index Number for System Realtime Messages is always "0xF". ### Additional notes [KORG SQ-1 issue reported in the Discord](https://discord.com/channels/980245825202552942/1508134403719696566) seems to be caused by the same issue.

MK3 page (scroll down a third of the way down for version selection)
https://www.native-instruments.com/ni-tech-manuals/kontrol-s-mk3-manual/en/keyboard-settings

If you use MIDI 2.0 mode and the new driver, Windows will automatically translate to MIDI 1.0 for apps that need it.

Pete
Microsoft

Naor_Hazan · August 10, 2026, 11:56am

The issue ive demonstrated in the video was the Kontrol on MIDI 2.0 and the driver set as ive sent in the screenshot later
its good to hear that a fix will be pushed eventually

so until this update will get pushed by microsoft we have this workaround

Thank you pete!

Psychlist1972 · August 10, 2026, 3:08pm

To clarify

The issue ive demonstrated in the video was the Kontrol on MIDI 2.0 and the driver set as ive sent in the screenshot later

The fact that the combined MIDI 1.0/MIDI 2.0 driver is in use doesn’t mean the MK3 is actually in MIDI 2.0 mode. The new driver supports both MIDI 1.0 and MIDI 2.0.

MIDI 2.0 mode is a setting you need to make on the Kontrol itself. The setting is on the page I linked to.

If you were in MIDI 2.0 mode on the Kontrol, this problem wouldn’t be a problem and so it would be something completely different happening and we should investigate further.

Pete
Microsoft

Naor_Hazan · August 10, 2026, 3:46pm

@Psychlist1972
yes im aware that to change the Midi mode on the mk3 is happening on the hardware itself
the keyboard was set to midi 2.0 when recording the issue video
the problem appeared when ive send midi clock. and wont happend if i wont. (and of course the old driver that you mentioned as a workaround)

Psychlist1972 · August 10, 2026, 4:39pm

Thanks for the additional detail.

This is an unknown bug then. I’ll need to look into it.

The important addition to the repro: the external device needs to be a native UMP / MIDI 2.0 device. This isn’t a MIDI 1.0 driver or device issue, and therefore Cubase is working fine. The problem is almost certainly in Windows.

Pete
Microsoft