Shared albums
I lost all my shared albums on my MacBook Pro but still have them on my iPhone. How can I get them on my computer?
MacBook Pro 15″, macOS 11.7
What has happened on your Mac, right before the Shared Albums got lost?
If you had disabled the Shared albumin Photos, it may take a few days before they will come back, after you enabled them again. Just ensure that the Mac is connected to Wi-Fi and and the Shared albums are enabled in the Photos > Preferences > iCloud.
However, the Shared albums can only come back, if they are still in iCloud. If the person who is sharing an album is no longer sharing it and removed it from iCloud, you have to save all photos from the album before you turn the Shared albums off. Otherwise you will lose the photos, because only the photos that are still shared will reappear from iCloud.