Photos Assign Location

I have entered locations, and I have copied locations from other pictures using Image>Location, and everything works as it should for me. I think I've seen this before, but, darn it, I can't remember how!

To narrow things down, try these steps:

• 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 

Those are the easiest things to try first. Then try these:

• 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. You can create a new Library by closing Photos and then option-clicking on the Photos icon.
• Make a new user and see if the same problem recurs with it
• Rebuild your Photos Library--close Photos and re-launch by option-command-clicking the app icon.

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.

Let us know what happens…

Do you mean you do not want the Photos library default of being in your Pictures directory but some other location? If so then just move that file out of Pictures to a new location. Then when you start Photos hold down the option key and specify new location.