Rekordbox usb unsupported device on XDJ R1

I have the latest version of Rekordbox running on a windows 7 os.

I recently purchased a 1tb usb drive.

I formatted it to FAT32 (eventually!) using a third party program as the default is ExFAT.

I've successfully imported all my music files and (eventually) organised them into playlists of less than 1,000 files.

I've successfully used the sync feature to export a few playlists to the 1tb drive, setting the device in preferences to xdj r1. Following advice on these forums, I've waited until export is at 100% and ejected the drive via rekordbox so that I get the 'creating playlist' window appears then disappears.

The XDJ R1 comes up with unsupported device no matter what I do.

I've tried a 32gb usb drive, formatted on a windows xp machine to FAT32 and then synced via rekordbox with the same problem. Also tried the same 32gb drive with just .mp3s and thats's the same too. Unsupported devic

Perversely, I found a usb stick lying around at work, synched a playlist via rekordobox and hey presto it worked in the xdj r1.

I'm losing the will to live as to why my 2 memory sticks won't get recognised.

the files  are all there in every PC I've tried so structure is ok.

thinking of rolling back to a previous version of Rekorbox. Will I have to re-import everything and do I have to uninstall version 5 or indeed will this help?