About a month ago, I noticed that for the first time in my history of using LR, my catalog was missing a significant portion of my images so I restored from backup. When I launched the backup, the program warned me that this catalog was not the current one in sync with the cloud and asked me if i wanted to switch sync to that catalog. I answered yes and after churning for some time, it never really stopped syncing and had a long list of strange errors on the preferences sync window.
After searching online, I tried resetting the sync data and trying again but had the same issue. I only really use Classic for a few tasks like HDR merge, third party plugins and printing. I figured I'd wait for the fall update to see if this issue was resolved but, unfortunately, it has gotten worse. Now, even after resetting the syn data AGAIN, after spending time syncing, LR will pinwheel and become unresponsive. If I come back after awhile don't force quite the application, it will have crashed the computer with a kernel panic! It never finishes syncing and is even slower than ever.
This is really making me rethink even using LR in the future especially with the slow progress in replacing the basics in LR CC with focus on half-working, consumer features like face detection.