One of my shared albums unexpectedly disappeared.

I created a shared album on my MacBook, uploaded photos, and invited another user. After creating the album, I also logged out of the photo background. After a whole day, the shared album was still displayed on my MacBook, and all the photos were still there.

However, when I checked my iPhone at the same time, I did not see the album that had been created, and the invited user did not receive a notification to join.

The next evening, I tried to resolve the issue by following other case scenarios: I closed the shared album on the MacBook and restarted it. However, the album I created unexpectedly disappeared, along with nearly 4,000 photos and videos (they were not in the Recently Deleted folder either).

I also tried restarting Photos using Command+Option, but it had no effect. The shared album I created did not recover either. (However, other shared albums created before and after that one still exist.)

How can I resolve this issue and recover my photos?