Hello Kirk,
Spontaneously gone as in deleted without any direction on your part?
Yes
Also the path to the external proxy storage was empty.
Again, spontaneously as in unexpected behavior?
Again yes
All of the new catalogs, or even existing catalogs that had external proxies working correctly spontaneously stopped working?
Yes, all the existing catalogs that had external proxies working correctly spontaneously stopped working.
Perhaps it could have been another problem:
There was a major Windows update (KB5013943) in the meantime after the PM+ update.
Since I have been working only in the navigator lately, i am not sure when exactly the catalogs disappeared.
So it could also have been the Windows update?
(on the mac system I had no such effects)
Greetings
Thomas