My issue: In LR Classic on Windows 10 using the standard Flickr plugin, ~40% of my 'regular' (aka, not 'Smart' collections) show zero photos within the collection. I don't pulbish via the Photostream from LR> This seemed to start in mid-August using a standalone version of LR (2015.2). I upgraded to a subscription plan a week ago, hoping that would fix things, but it did not. Of note, as far as I can tell all of the photos remain on Flickr, they just don't show in LR as being in the corresponding collection.
Any ideas as to what occurred here? The only thing I can think of is that I was testing out using the JF Flickr plugin to see if it was any better, before I ultimately decided not to proceed with it. Maybe something in the setup process wiped photos from the Collections within LR?
Would a reverting to a previous version of a LR catalog work here? Is that a simple process to do and can I revert back to the latest catalog if I need to (say, if reverting to an older catalog doesn't fix the issue).