MSU-1 on RA/SNES cores Series X not working!?

Hi all,
First off I have MSU-1 hacks running find on my SD2SNES/FX PAK PRO and have never had an issue. I have recently put Retroarch on my Series X and have tried both Snes9X and BSNES and cannot for the life of me get MSU audio to work. I've tried launching the manifest.bmls, which launch fine but I get greeted with a blakc screen on BSNES. I then tried the .sfc/.smc on SNES 9X with the .ips patch in the same folder, it reads the rom and tells me it patches it fine, but still no dice. I've re-patched and rebuilt manifests etc. to try different. solutions but have got nowhere. Any ideas anyone?

Many thnaks

Figured it out! You can't put the MSU files on a USB, must be on the internal drive.