How do i fix the locations in my Photo library?

Make sure location services is on, and enabled for photos is system pref>security and privacy> privacy. If it already is, toggle it off and on and reboot/clear NVRAM if on an intel Mac.

If that doesn’t fix it try repairing the library (apple has a support article you can use).

if repairing the library doesn’t fix it I suggest creating a new photos library on your Mac and letting everything sync back down from iCloud.

Apple has some good support articles on how to make/manage photo libraries on a Mac. If I get the chance I’ll come back and add them.

Something those articles don’t make clear is you need to make the new photos library the system photos library to enable iCloud photos on. With the library open, you do this by going to photos (next to apple) > preferences> Use as system library

note: making a second library doesn’t affect the first one

Locations are looked up on the fly from apple servers.

If that is happening then somthing is getting in the way of the apple location servers, or they are down. Though they are unlikely to be down for days at a time.

Make sure your internet connection is OK. Have a look at any firewalls or security software you may be running. If you are, then disable them. If it happens on the phone, does it happen if you disconnect from wifi and use the cellular data (or vice versa)