Cubase 9.5.2 Pro - Freezes on mixdown

I have just discovered I have this exact problem too since updating to 9.5.21 - all was fine prior to that. When ever the freeze happens, there is a massive spike in CPU usage (monitoring it with Stats menu) - it goes up to nearly 100% for all 4 cores then drops again. This happens every 2 to 3 seconds. Tried with both mp3 and wav export. It does it without any plugins enabled as well. I am on a Mac Pro with 10.13.4 installed - 3.7 GHz Quad-Core Intel Xeon E5 - 32GB RAM. Interface is a Saffire Scarlett 18i8.

I have very long mix downs that take up to ½ hour and would normally be able to work on other stuff with Cubase in the back ground, but this makes it impossible to do so.

Martin, I have tried it with zero VSTs and a single VSTI. It doesn’t matter which VSTI such as truepianos or NI Massive.

I am updated to the latest MacOS (High Sierra 10.13.4)

Current workaround is to enable real-time mixdown which does not show the problem.

What Audio Devices do you use, guys? What Buffer Size?

Btw, I already reported to Steinberg. But I can’t reproduce it in my macOS 10.13 system so far, so I try to get more info from you.

Saffire Scarlett 18i8 - tried it at 3 different buffer sizes (small, medium & large) + tried changing the interface to something else. Still the same, so not sound device related.

I am having this exact problem here too, big CPU spike while exporting, even just exporting audio with no plugins, causes the whole system to freeze for 2-3 seconds at a time.

High Sierra 10.13.4 - cubase 9.5.20, mac pro 5.1 12-core.
Problem occurs with different audio interfaces and different buffer settings.

interesting footnote. the problem stopped for me but not for any obvious reasons. I installed Reaper and rendered a short midi file in Reaper and Garage Band to see if it was system wide or just Cubase.

After doing that, I went back to Cubase and could not reproduce the freezes. This may be unrelated or perhaps that was enough to resolve an issue with CoreAudio.

RME babyface - 128 through 1024 sample buffers all had the same issue
UAD software + satellite installed

Interesting, thank you for the info.

@method1 are you definitely on 9.5.20 and not 9.5.21? If so, then I wonder if the problem is MacOS 10.13.4 rather than the Cubase update?

Out of interest, I went back to 9.5.20 via time machine and still had the problem with projects created in 9.5.21, but not new projects I created in 9.5.20.

Having this issue on 9.5.20 & 9.5.21
I also tried going back to 9.5.10 with the same result, so it’s probably got something to do with Cubase on 10.13.4.

I am running 10.13.4 here also. Note the issue no longer happens and I am still running 10.13.4.

Unfortunately still having the same problem, realtime export is also problematic because I get a cpu overload during export, even with just a simple audio file and no plugins.

This as an example of the type of CPU spike I’m seeing with even the simplest exports while testing this issue.
I have also repeated the experiment with Ableton Live which is not exhibiting this behaviour and works as expected.

Exactly the same issue here!

iMac 5K, macOS 10.13.4., RME Fireface 802, Cubase 9.5.21. Never had this a few updates ago. Now I can’t get rid of it.

I’m mostly doing real-time mixes so I can live with this but it’s definitely quite annoying seeing my whole system freeze up like this for a few seconds multiple times.

Can any of you say, if it’s macOS 10.13.4 related only? Anybody here on different macOS version (10.13.3 an older)?

For info, I tried this, and it didn’t work for me - still having the issue.

Windows 10. Freezes on start of offline mixdown at 0% and button is blank (‘cancel’ I think). Got it to work once only.
32 GB of RAM and never goes above 50%. Tried all manner of resolution and depth.
Got a CPU overload message when trying to mix in real time. Core i7
Rebooted PC - no avail.
Cubase 9.5.21 and same for 9.5.10 beforehand.
Steinberg UR44 and that seems to be working correctly.
I was trying to submit a ticket to Steinberg but went through a roundabout of websites and got nowhere. How can I submit a ticket directly?

Log in to the Steinberg website and go to your account “My Steinberg”. There’s a link for ‘My Support’ - click that and you will be presented with a form fro creating a new support ticket.

This is another issue. As far as I know, this is only the freeze of the progress bar, but the whole system is not frozen. Or am I wrong?


By any chance, do you use any plug-in(s) on your Stereo Out/Master Channel, guys? Could you try to Bypass/Remove it, for a test?

It happens without any plugins anywhere.