HI,
Perhaps Arturia don't know what's going on. Perhaps it's not a Arturia issue. I can't tell. Perhaps Arturia even can't. But perhaps that's why they have'nt been able to help you, - at least yet.
Which precise version is your OS?
Do you use multiple screens?
Do you use any high resolution scaling? If so, which scale?
Do you place your plug-ins in default folders?
Have you tried both VST2 and VST3 64 bit plug-ins? Are your issues with AU plug-ins? Do all plugin versions have issues?
Do you have GUI issues when you open the standalone applications?
Some links in case they can help to understand what causes the issues:
https://help.ableton.com/hc/en-us/articles/115001443850-VST-AU-plug-ins-reset-to-default-presethttps://help.ableton.com/hc/en-us/articles/209773265-Troubleshooting-a-crashI know you are in a difficult situation. I hope you somehow get it resolved. As it is, then it's hard to tell, what's going on, and why you get different issues.