External card not recognizing audiobooks in mp3 format

>>Maybe an experienced SanDisk owner of an older Clip model and a Clip Jam / Sport can tell us if the music and audiobook library files created by one player on a micro SD card can be immediately used by the other player.

I was able to just move the external card from one Sansa Clip to another with no problem. I was NOT able to move that same card to the Sport Clip. I got the file format not supported message.

>>Also, I did not know that the Clip Sport could format the micro SD card (only the internal memory of the player)?

It was one of the options, so I tried it. I still get the file format not supported message for mp3 files copied to the external card.