Sync issue wihout files stuck of error message

Hi, I'm using LC vers. 14.0.1 on Mac. I've got a few folders which are synchronized with the cloud, and that usually works pretty well. Recently I added 122 new pictures to a folder but only 7 (!) of them got synchronized. I don't see any error message

and in the sync preferences window it says there is no sync going on or files stuck:

I've tried to figure out if there are any differences between the pictures that sync and those that don't but found no reason (i.e. smart previews or not, files missing, videos or others).

Any ideas how to "force" the upload to the cloud of those pictures? Thanks!