Today, I wanted to add my husband's photos to my Photos library on my iMac. I plugged in his iPhone and accepted the trust notifications. However, to my surprise, only a few photos showed up to import into my Photos library. Hmmm...strange. I have an easy solution if you're running into this same issue!
If you use Photos.app with multiple library files, then sometimes it can be confusing which library file you're viewing. Here's how to determine your Photos Library file name.
Learn the three-key command that allows you to permanently delete photos from your Photos Library, even from within albums.