Hi Andrea,

As the last attempt:
When you install AutoCAD it also install Autodesk 360 application which is running at system startup by default, even you don't launch AutoCAD. When you remove AutoCAD, it also remove Autodesk 360 app.
What if you will try to prevent Autodesk 360 from launching at system startup after you install AutoCAD? You need to remove Autodesk 360 from Startup items in Users pane of Mac OS System preferences, than try to see if the problem with graphics glitches still there.

Maxim