moving cropped pictures blocks photos

Well, restarting is always a good fist step, but I bet you knew that. And don't try to re-install Photos! Are you running macOS 11.4 Mojave, or is that old info?

The first things to try are these:

• Restart the computer (like ryane77 said, of course)
• Rebuild your Photos Library--close Photos and re-launch by option-command-clicking the app icon.
• Make a new user and see if the same problem recurs with it
• Use another library if you have one, or make a small test Library with a few pictures in it and see if the same thing happens.
• Start in Safe Mode (different for different computers) This bypasses certain potentially disruptive processes.

           Start up your Mac in safe mode - Apple Support 

The idea is to find out if the problem is with the Library, with your account, or with caches and login items, and stuff like that. One of these steps may acutally fix the problem, but their failure to work is also diagnostic.

Hi CESNET,

If the Photos app stops responding, the steps in this article will help: If an app on your Mac stops responding, closes unexpectedly, or won’t open.

1. Quit and reopen the app

Quit the app, then open it again. If the app won't quit, force the app to quit. Then check to see if the problem with the app is fixed.

2. Restart your Mac

Restart your Mac. Then check to see if the problem with the app is fixed.

3. Check for updates

To see if updates are available for the app, open the App Store, then click Updates. If updates aren't available for the app, update the software on your Mac. Or if you didn't get the app from the App Store, look for updates to the app on the app developer's website. Then check to see if the problem with the app is fixed.

4. Reinstall the app

Delete the app. When you do this, you might lose data that was stored in the app. Then redownload the app. If you didn't get the app from the App Store, redownload the app on the app developer's website. Then check to see if the problem with the app is fixed.

If the problem persists, you can further isolate it by testing in a new administrator account. If needed, this article will guide you through creating a new account. Knowing whether the issue happens in a new user account will tell you if you have a system-wide issue, or if it's specific to the user account: Add a user or group on Mac.

Kind regards.

"That's often a great thing to try first"

Not really. Please be careful, Richard. I would never recommend a library repair as the first thing, only as the last resort, if all more harmless measures have been exhausted. It can be a very expensive fix, if the library is syncing with iCloud, it will result in a new upload to iCloud, that may take weeks for a large library. And if the library is badly damaged, it can make the damage worse. At least, the library should be backed up, before repairing it (without overwriting the last good backup we have). See Apples warning here: Repair your library in Photos on Mac – Apple Support (UK) "Important: You should back up your photo library before repairing it."

And it must not be repaired while residing on an incompatible external volume.

Interesting-- I have not done a repair on an iCloud-synced library. My iCloud library is one that only has "favorites" and recents in it, so it doesn't get messed with, much. iCloud syncing has made some things more confusing....

You are right, Richard. iCloud is certainly a great help to keep our devices in sync, but some things are now much more difficult.

I avoid to have my iCloud Photos Library repaired, if possible. When a library is repaired, Photos may recover lost and found items in the library, that are not yet in iCloud, also the structure may change. So Photos is making a complete new sync to compare it with iCloud. This may take several days, and I had frequently to add many custom faces back to the People back.

That's often a great thing to try first. Glad it worked!