iCloud Photos won't allow sync this Mac
I have a large Photos library (200K+ images, 2K+ videos) on the 4TB plan. The Photos library resides on an external 8TB drive.
Apple ID is the same on all devices. Same iCloud account. Operating Systems on all devices current.
Noticed recently my library was not syncing with iPhone and iPad. Their photos appear in each other's library but not in my Studio library. And the Studio's images do not appear in those device's library.
It appears at some point the main library was deselected as the system library, so I selected that. An hour or so later the library appeared. No updates appeared on the external devices. No messages at screen bottom on any device. My Studio library states 211,767 photos, 2,075 videos. (Studio) No sync or loading notice.
iPad and iPhone both state they have just now synced with iCloud. (212,749 photos, 2,082 videos)
There is 2.24TB iCloud available.
Little Snitch reports no significant internet traffic aside from housekeeping traffic.
If it is syncing in the background, should there not be notice someplace that states a sync is in progress?
Thanks for your thoughts, shared experiences.