I had this same issue, it would "appear" to continue to try to re-upload my entire library after taking forever to process.
I also experienced similar behavior with iCloud Drive (I would download files, get repeated 'Couldn't communicate with a helper application', and then an icon would appear next to all of my files that said "uploading" when I hovered over it.
After awhile, trying to manually access photos resulted in a "resource isn't available"/"couldn't load resource", and that was enough to make me "internet recovery" back to Mohave for now.