USB stick not recognised in GLD80

I have a USB stick that is formatted to FAT32, recognised, readable and writable in OSX El Capitan, but when i plug it into the FLD80 (with my show file on it) is not recognised. A colleague’s USB stick is recognised instantly. A few questions arise:
What standards apply to USB sticks for the GLD80?
Are there supported models of USB stick?
Why would one USB stick not work?
Is FAT32 (which should be readable by every OS) the wrong format?

Is it not recognising the flash drive at all, or can it just not see the show file?

Chris

Not recognising the USB stick at all.

I know that there are many USB drives that don’t work with the QU series so we shouldn’t be surprised that a few don’t work with the GLD.
I haven’t run into any yet but others have.