Hi Patrick, try this: On the PC > Format, Choose options FAT32, Reset Allocation unit size to Default, Don't do a quick format, do a full low-level format. It takes longer but this method so far seems reliable for memory sticks that have been temperamental with CDJ/XDJ so may also work with external ssd..
Format will take a long time (just let it run overnight) then export your playlists from Rekordbox to the device.
On the plus side, it's good to hear that CDJ3000 don't sound as fussy about memory sticks / ssd.