Hello
Since several days, my colleague is encountering strange bugs in Cubase Pro 10.5.20 / Win10, mainly with Nexus 3, but he said that sometimes UVI Workstation was also affected.
We opened a ticket at reFX but so far no solution 
First thing is, that with UI Hardware Acceleration on and two instances of Nexus 3 GUI open, the song position indicator in Cubase freezes the moment it hits any note from opened/active N3 and remain frozen up till the last sound from N3 quiets out. It almost hangs the Cubase, because we canât stop the playback while the sound is still coming from Nexus.
But this is not happening with only one N3 open at a time.
Second problem with h/w acceleration on - the N3 GUI is often just a blank white rectangle. When poiniting inside with the mouse, sometimes only some numerical parameters are showing.
When we disabled UI Hardware Acceleration in N3, this particular problem goes away, but another one appears - in some projects when we open any dialog box pop-up (like reset library filters) it doesnât close at all, even after closing N3 GUI. These pop-up boxes disappear only after closing Cubase. And at the same time N3 doesnât âseeâ the included libraries, the library screen is empty.
The problem occurs mainly, when Nexus siths in a project folder with many other tracks. Like ~80 tracks in a folder, VSTi and MIDI, different plugins, both from Cubase and 3rd party ones.
Rarely, when all instances of N3 are in own folder or even not grouped at all (top level tracks).
We tried to switch graphic cards between intel iGPU and RX550, changing gfx drivers and so on, no luck.
Maybe itâs a problem with Cubase, but it was working ok like a week ago. Maybe itâs some bug introduced by last Windowsâ updates, with some of the system libraries, I donât know.
Iâll appreciate any help 
After several yesterdayâs tests we have 2 conclusions 
-
The freezing song indicator (and partly freezing the whole DAW) is a problem between Nexus 3 and graphic card, when UI hardware acceleration is on.
Tested on Cubase 10.5 pro and Studio One v4 Pro - on both DAWs, open 2 instances of N3 GUI caused freezes when using AMD RX550 card (different drivers, new, old, WHQL or not), but with intel iGPU it worked ok. So far.
-
The disappearing GUI (acc on) or dialog/library problems (acc off) are most likely caused by a faulty Cubase memory management, and probably inside the folder tracks. And itâs not only N3 problem.
Like i wrote, we have a folder track with ~100 tracks inside (MIDI and VSTi).
This folder apparently hits some memory limit and cannot load and allocate all the needed memory in one go, during loading of the project.
When we moved some of the VSTi tracks/subfolders to other folders outside, or directly to the track list (top level), looks like the problem is gone.
For example, when we moved âoutsideâ the Nexus 3, the UJAM guitars and the UVI Workstation folders - it was ok.
But when we moved out only one folder, with Nexus 3 tracks, the limit hit around 5 instances of N3.
IIRC only 4 tracks in N3 folder could activate proper GUI, when the rest of N3 tracks were disabled.
I mean, we enabled only one N3 track and reloaded the project - ok. Then 2 (reload), 3 (reload), 4 (reload) - still ok, and around 5 N3 instances - the GUI is gone from all the N3 tracks.
Also, the UVI Workstation plugins started to show similar problems - part of UI was blank and dialogs were faulty.
It means, that the one big folder is causing issues.
(BTW disabling tracks in Cubase apparently releases memory and makes saving/loading projects much quickier.)
Also, we found that when the GUI is affected, disabling and enabling the track brings back the proper GUI - apparently Cubase is forced to reallocate memory for the tracks.
Now we probably will try to find proper driver / settings for RX 550 to work.
Or check, if the Cubase v10 works ok, because v10.5 is quite a bug-fest, looking from other posts here 
Best regards
Mike
