Kirk, at the risk of jerking you around here, I have to take a step back on this issue after additional testing. The monitors have nothing to do with it.
My more recent folders all contain .XMP sidecars. I thought it was an issue on all folders because opening any of these more recent folders crashed the apps. However, in testing the monitor issue, I happened to open an earlier folder with no .XMPs. All was well. Again opening a more recent folder crashed the apps. Isolating files pointed to the .XMP files. I have now gone back to folders from years ago where .XMPs were present. Attempting to open a contact sheet for any folder containing .XMP files crashes the apps. Am I missing something on the handling of .XMPs - I don't remember this being a problem in the past.
My sincere apologies for the mis-information.
...Bill