Yup, CUDA remains much more stably accessible when the PyCharm debugger is terminated before suspending a machine.  I can use it all day with multiple suspends.  Overnight CUDA did crash and I thought I had terminated the debugger but perhaps not.
Anyway, a workaround to the problem, most of the time, seems to be to terminate the PyCharm debugger before suspending, otherwise CUDA will almost certainly become inaccessible (at least on my Ubuntu 18.04 system).