Blank titles/album art


Hopefully I'm posting this in the right area - apologies as I'm new.

Quick question: I was in the middle of tagging albums, no problem, when suddenly the first 3 tracks of every album all have blank titles and no album art. Tracks 4 and above have no issues. It's always just the first 3 files and I've tried multiple albums.

The filenames themselves display the titles, but the Title/Album Art columns on the left are blank. I keep trying to edit the tags/add the titles in the Title column, but as soon as I click off them, they revert back to blank.

I might be missing something as I'm still getting used to mp3tag, but is there a way to permanently embed the titles/artwork without them disappearing? Doing the auto-numbering wizard changes the filename from 01 - Track Name to: 01 - ...

Thanks in advance

check, which tag-versions you read, write and delete in
If you read and write APE, it could be that you see the contents of APE tags which are asynchronous to the ID3Vx tags.
What happens, if you switch off the reading of APE tags?

If you intend to renumber with the numbering wizard, see in which order you have the files if you tick the option to reset the counter per folder.
The counter is then reset whenever the previous file is in a different folder than the current one.
Sort the files by folder so that they are grouped together for each folder.