This has been going on for days, hopefully someone can help. I recently started to sync my new 2018 catalog, which I put off because it takes so long to resync the photos from the older catalog. After a couple days, the sync settled at 92 and won't move. The develop module has become crazy slow, making it very hard to get work done. I've already tried the fix of renaming the sync.lr file in Library, and it still settles at 92. Under Preferences>Lightroom Sync the activity shows that most all photos are still downloading and that 92 photos are Pending.
I would normally thing that it just needs to work itself out with time, but it's been at least 5 days at this point. Any suggestions?
So I just discovered today how to fix my similar issue with being stuck syncing 2 photos forever. Under Lightroom/Preferences go to the Lightroom Sync tab and press Option/Command (Mac) and you'll see 2 new buttons in the bottom right of the window. Choose "Rebuild Sync Data". This cleared up the issue for me. I no longer have the Syncing 2 photos in the upper left of my LR window and everything is in sync. Hope this helps.