USB stick not recognised on CDJs

Had a problem today plugging my SanDisk 128GB USB (3.0) into the CDJ’s. The CDJ’s kept trying to read the USB but didn’t recognise it.

 

This is weird because just before I finished sync manager on rekordbox (on my Mac) and it all went smoothly. I’m pretty sure it’s not a formatting issue because if it was then surely rekordbox on my laptop wouldn’t have picked the USB up? The USB is formatted to MS-DOS (FAT32).

 

I’ve heard it could be because of the size of the USB being 128GB maybe being a problem? But not sure?