I took 4 photos on Thursday night with Lightroom CC on my iPhone 7, and it has been stuck syncing those 4 photos since then. There were also some photos imported from the Photos app into Lightroom CC that were also stuck in the same pending upload. I removed them from Lightroom, so the only photos left in the sync are DNG photos made with Lightroom.
I tried signing out and back in, and that hasn't cleared the problem. I deleted the Lightroom CC app and reinstalled it. While that fixed the problem, it also lost the 4 photos since they hadn't been uploaded. I restored my iPhone from my last backup to get them back, and it is now back at the same stuck sync on those 4 photos.
How can I clear whatever prevents these photos from uploading? I don't want to delete the photos, and I want to keep the DNG files for further editing on my Mac if I can ever get them to sync.
They weren't in an album, and making edits didn't change the pending upload status. I finally solved it by exporting the original DNG files to an iCloud directory and then deleting them from Lightroom. When I reimported them the syncing worked again. I lost the edits, but I was able to edit again and have that sync with no trouble.