Photos not uploading to iCloud, Photos app hangs when copying or moving photos

The Photos app has always worked flawlessly for me. I have a Sony DSLR that I sometimes upload photos from onto my Mac. Never had a problem before. Today I uploaded photos, and then edited two of them. Neither of these photos will upload to iCloud, they don't even appear in the thumbnails when I try to upload them manually. When I try to copy and paste, or drag and drop, the Photos app hangs up and I get the spinning wheel of death. My first guess is that Photos is corrupted somehow. I've run virus scans and so forth, and nothing detected. So now what? Why is it only the edited photos that won't upload to iCloud? And how do I get Photos to behave and stop locking up? (And yes, I've restarted my Mac. I have a 16" MacBook Pro running Monterey.)