I had trouble with a flash drive, too many songs. Found a post that says no more than seven folders and two hundred and fifty five songs in a folder. Made a folder and put half my songs in it and left the other half out of the folder. So far it works. Hope this helps.

 

Well, I use a flash drive with 50 folders in the root directory; about 240 folders total, counting sub-folders; and over 3,000 tracks. Works fine in the USB2 port (behind the center console) of my 2021 Trailhawk with Uconnect 4C system.