Same problem here too. I have 3 collections that were synced before. It worked like a breeze. Yesterday, I've deleted a few photos from those collections (with Lr Desktop) and made many changes to others in the Develop module. Going in Lr Mobile, the deleted photos are still there and the photos that were developed are... like they were before the changes. Kind of frustrating! :-) For the sake of it, I've started a new collection (with 119 images). To no avail. It is not showing in Lr Mobile. In Lr Desktop, I get the "Syncing 119 photos" above the identity plate at all times.
I connected to my account via the link above (Adobe Lightroom) and it shows the same problem, namely the deleted photos are still there and the changes made in the develop module are not showing.
Seems to me that the new versions of Lightroom desktop and Lightroom mobile have... well... some bugs.
Waiting... Hoping... :-)
Claire