synchronising photos and iCloud
My photos have stopped synchronising to my Mac. I've checked and rechecked the settings for photos and iCloud and all are correct. I have a MacBook Air that is synchronising perfectly but not my Mac.
Good. That means the library is the current system library. Try logging in and out. Your library may also be corrupt. You could simply create a new library, make it the system library, and enable iCloud photos (assuming everything is in iCloud) and the library will download/rebuild.