Tracks are found when you connect in MTP mode. Since you are using a MAC you cant do that.
Your solution is circuitous. Connect to a friends PC in MTP mode.
Copy all the content to the PC. Reformat the player, unplug and set MSC mode.
Connect the player to the PC in MSC mode. Copy the content you want to Keep to the player.
Delete the content from the PC if you want to .
Connect to your MAC, and you can do what you want with the content.
