Tagged in the Program but not outside?

Hi. New to the group. Anyways...never had an issue with MP3Tag until tonight. I tagging a bunch of music files and going back in the folder to check when I came across 2 files I know I tagged, only to find they were not tagged. I opened MP3Tag and I see them tagged...complete with album cover pic etc. But I go to the folder and the file and they are not tagged. No cover art or anything. I opened the properties of the files and no tags. What happened? Thanks for any help.

Perhaps an example might help. File type? Id3v1, v2, ape? OS?

It says ID3V2.3. It's an MP3...still using windows 7 at the moment. Like I said...no problem with any others...just 2 files. Started tagging other songs in the same folder below these 2...no problem...

I’d test them for validation of the tags, or possibly even file corruption. Try mp3diags.

I ended up doing an online conversion and it worked fine after that