About a week ago my Lightroom Mobile stopped syncing.
Since then I have tried the following with no luck:
Deleting the sync.lrdata folder
"Delete all data" from Lightroom preferences
Logging in and out
Removing all images from sync collection and adding them again
Re-installing Lightroom mobile on iPad
Tried syncing another catalog with only 4 images
On lightroom.adobe.com it says: You have no synced collections.
There was a misconfiguration at the back-end of your account please try to re-sign-in and let me know if it's working now.
Btw. Are you running Lightroom 5.4 or 5.5?
I am running 5.5.
It appears to be working now.
Syncing is in process.
I posted about this same problem in another thread. I suspect my issues may be on the back end as well. I keep separate catalogs for all of my clients. When I first tested LR Mobile, I wasn't aware of the one catalog limitation, so I ended up creating a separate one for new work that I want to sync with mobile. So maybe I have multiple catalogs on the server?