Please don’t get frustrated.
I have 16,320 MP3 files.
Let’s just say they’re not very well tagged because they come from different sources.
My method is as follows:
I completely cleared the tags using Mp3Tag.
I added the entire directory to Picard, pressed Scan, and saved the tags to the files.
I exited Picard.
I reopened Picard and checked this option: Ignore MBID.