I can confirm that the problem only seems to occur and seems to occur fairly reliably when I suspend and resume, but with PyCharm active and perhaps my debugger on.  I just tried twice to cause CUDA to destabilize w/o PyCharm on and suspending / resuming, just using ipython to check for availability of cuda.  Encountered no problem.  Then I tried to destablize CUDA by having PyCharm on but not debugging.  Also encountered no problem.  Late today, I’ll try to try to again, but with the debugger running.  I suspect that’s when it’ll fail–which should give me a good way to avoid breakdowns.
Also, tried rmmod nvidia_uvm (good suggestion–makes sense).  Unfortunately, it gives an error msg saying nvidia_uvm is in use.  I tried a variety of things, including removing other nvidia kernel modules, but whatever I do nvidia_uvm ‘is in use.’  I have to have ‘sudo prime-select nvidia’ in place or otherwise cuda is inaccessible, but the moment I use ‘sudo prime-select nvidia’ all the nvidia modules load.  I can go back to ‘sudo prime-select intel’, but it takes a reboot to have any effect.