zala19 wrote: Yes, but they still don’t work.
What did you "drag?"
You that your "External drive is suitable for Mac! " but you didn't provide details. How is it formatted? How are the permissions selected?
It could be that the video is corrupted. Have you tried to export the video and play it with a different app. When a video is a problem I always try it in the app VLC. It's open source and not at the app store.
When something goes haywire for no clear reason, I usually try these things:
- Restart the computer (of course)
- Re-start in Safe Mode. This bypasses certain potentially disruptive processes. Safe Mode is different for different computers, so see this:
Start up your Mac in safe mode - Apple Support
- Make a new user and see if the same problem recurs with it
- You've already tried using another library-- that's good troubleshooting
- You also Rebuit your Photos Library!
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 fix the problem, but their failure to work also helps figure out what's happening.