Album Art not shown out of Mp3tag

I have made and inserted and save album art 640x640. inside mp3tag everything looks alright but neither file or when played on various player the image is not shown

Player problem
Apparently, you use only the WIndows Explorer and WMP as test environment.
See what happens if you export the covers as file with the name "folder.jpg".

Sorry, I don´t understand. I have pased songs to mobile and opened them to its player ad also it doest show, neither the file has the picture

It looks like at least some of these are wav files. These won’t store embedded information like album art that I am aware of.

Mp3Tag is able to save tags - albumart included - to wave files. The problem is that most players can't cope with tags in wave-files.

This is more correct, thanks for clarifying. And to that point, I do believe Windows has no way of using embedded artwork on wav files for thumbnails, nor in wmp.

Yes, you are right. I overlooked the file type wav. So it is even more a player problem.