Hi, I have been experiencing this cloud sync issue with some images on my Android (6.0.1) Lightroom Mobile app (v2.1.1).
It seems to mostly happens on images where I have made edits in the desktop app and are set to a synched collection. The images seem to have synced to the phone but the actual image contents don't show up.
From the images below you see the collection view there is a grey box on the top left where the image thumbnail should appear. The second image is the develop view of the image which shows the metadata but the image never comes up. The cloud icon seems to try to sync but then shows the paused icon and "All up to date note". If I export the image from the phone, the JPEG of the original image is created in my gallery without any edits made on the desktop.
I have tried restarting the app and the pone multiple times. Other images seem to sync with no problems. Any help is appreciated.
Has Lr Desktop fully synced the photo? Could you try to make a tiny edit and let the phoo re-sync?
Sometimes it happens when you make an edit and quit Lr Desktop before the meta-data changes have been fully synced.
Let me know your results