Could it perhaps have something to do with the fact that I have Windows configured to launch folder windows in a separate process?
Usually, all file explorer windows, including the desktop shell, run in a single explorer.exe process. If one file explorer window hangs or crashes, it will cause all file explorer windows running in the same process to hang or crash until the process restarts.
So, for increased stability I have Windows configured to launch folder windows in separate processes.
Perhaps that's somehow interfering?
Unfortunately, now that the problem(s) occur far less than they did before, it's difficult to test whether or not that setting is actually causing issues. I can disable it, but I think to be sure that was the cause I'd be looking at 1 to 2 weeks of testing to see if the issue occurs again.