Ender 5 S1 with Sonic Pro USB Drive sometimes not recognised

I have been using my Ender 5 S1 for a couple of weeks using it with a Sonic Pro with no problems. Today I printed a couple of items without any problems, however after loading a new gcode file onto the USB drive and plugging it into the Sonic Pro, the USB drive was not recognised. The drive is recognised by my laptop. I’ve also used a different USB drive and that also is not recognised by the Sonic Pro.
I did a factory reset/calibration and the USB drive is now recognised
intermittently, I’m wondering whether the USB port on the Sonic Pro is going bad ?
Any help greatly appreciated.

There are 4 ports on the Sonic Pad, tried all of them? Tried another USB stick?