I have successfully used DL Mobile for some months (currently: some 3+k photos in Adobe's Photo Cloud, in 56 collections).
Some two weeks ago sync on DL desktop went erratic, i.e. sync attempts were always active according to the spinning wheel in the UI, but no sync happened. Right now this has changed to a status of no sync indication on Mac DL desktop whatsoever (no spinning wheel). No upward sync of changes from DL Mac to the Adobe Photo Cloud is happening.
BUT: Up-sync to the Adobe Photo Cloud from iPad works: For example, change results can be seen immediately via browser in Adobe's Cloud collection library. AND, strange enough: the changes from iPad via Cloud are synced down to DL desktop on the Mac as well (without any sync indicator visible on DL desktop though).
What can I do to get back to full functioning?
Could you please send me a LR Desktop diagnostig log - best as a private message with a downloadable dropbox link.
You can trigger the log via LR Desktop preferences -> Lightroom Mobile and when you hold down the alt key you will notice a generate diagnostic log button