Whoa !! You are asking for help with your Sony MP3 player from users in the SanDisk Forum ??
I have not seen any discussions of the Sony Walkman players within this Forum.
GENERAL ADVICE FOR SANDISK PLAYERS
For my SanDisk Clip Sports I always use ID3 tag version 2.3 and I delete all other tag format data from my mp3 files (v2.1, v2.2, v2.4, APE, etc). I use ID3 v2.3 (ISO-8859-1). I use the software “mp3tag”.
I use jpg album art files that are approx 250 x 250 pixels and 72 DPI. When saving the jpg file. I clear all “EXIF” data (if exist).
I make sure all current embedded album art is deleted from my mp3 files. Then I embed one 250 pixel jpg file into the mp3 files. (Maybe the player will get confused with multiple embedded art files??)
A handy trick with SanDisk players is to delete all embedded art from a subfolder of mp3 files. Then you can save one corresponding album art file as “folder.jpg” in the same subdirectory with the cleaned mp3 files.
->Sometimes just deleting all non-v2.3 tag data will do the trick of displaying the current embedded album art. (Yay !!)
->PNG album art does not work for me.
->Large size album art (default from iTunes) does not work for me.
->There is a whole alternate reality of details to get album art to display with “m4a” files that use ID3 v2.4 data.
If you have a few mp3 files that properly display their embedded clip art, then try to identify the exact ID3 tag properties of these files and the exact properties of their embedded clip art file ??
I like to use the program “irfanview” to adjust my clipart files before embedding into mp3 files.