First, I've found usb flash drives to be a crapshoot. Some brands work, others are not recognized. They're not all equal.
Currently I've found success with a Samsung 32G. Formatted Fat32 and the files are either MP3 or Apple Lossless (MPEG-4). It is recognized and music plays 5 seconds after I plug it in and it is previously indexed.
I just leave it on "Shuffle" and it plays all 3,000+ songs from ACDC to ZZ Top with stops at Mel Torme and Keely Smith. (Yes I'm old)
Had a 16G Sandisk that worked and now it doesn't. No clue as to why. Arizona heat, maybe? Didn't bother to reformat it just tossed it.
Second, stick with brand names.
Foosungtaint or Songgobye and you're asking for trouble.
Currently Amazon is selling some fake flash drives (I know! Shocking right?). Listed as 1TB or 2TB and are only good for maybe 16G or LESS!
Gibson Research has a free program to test drives and find out if they're genuine.
https://www.grc.com/validrive.htm
Good luck and I hope this helps.
Edit: Forgot, this is in my 2020 Silverado LTZ.
Gotta have that music!