Google Music Player Album Art displaying incorrectly even after tagging with MP3tag


I live in Canada so I can't go on to the web portal for Google Music. I downloaded MP3tag to try and fix my album artwork however it's still displaying a number of files incorrectly despite them displaying correctly in windows explorer. Anyone know how to get Google Music player to accept the MP3tag info?

No, I haven't got that programme (?).

The first idea would be to delete the file from the programme, make sure, it is not saved in some kind of database anymore and then reimport it.