Cover Art

I have a large collection of MP3's that I am trying to update the Tag info. I noticed that more and more of my mp3's were not showing cover art withing MP3Tag app but I recall them having art on my mp3 player (non-ipod). As I was working through my files I noticed that when I played some of my mp3's that Windows Media Player would display cover art that did not show up in Mp3tag app. How is this possible? I know when I ripped my cd's that I made sure that the cover art was captured. How does WMP show the art but Mp3tag doesn't recognize them. I could save my self hours upon hours of work if the app would recognize this. Please help!


WMP maintains a library and a collection of thumbnails - so the displayed images could very well come from there.
Also WMP uses the files folder.jpg and albumartsmall.jpg to display covers ...
So you should put more trust in mp3tag's display than WMP's: if mp3tag does not display any albumart then there is none in the files.
If you want to unify your collection you could proceed as follows:
Load all the files into MP3tag.
Execute an "Action (quick) of the type "Export Cover" - enter as name %album%.jpg
This saves all existing covers into the file system and the local folder.

Then apply a filter:
%_covers% IS ""
Select all files and execute an "Action (quick) of the type "Import Cover" - enter as name %album%.jpg
This should import all images from the file system - if there were any.
Refresh the filter by pressing F3 twice.
Ideally the files list is now empty. If it is not then you see the files without cover but you could try to import images from the folder.jpg file - if it exists.
So execute the import cover action again only this time enter as file name "folder.jpg".
Refresh the filter.
You would now have to search for the missing covers - e.g. with the function "Tag sources - Cover art".