Issues with losing bpm sync

hi just wondering if you could help - I've had the Xdj rx for a week or so and I've noticed that when I've got 2 tracks on sync, and I'm using the master deck - the bpm sometimes reverts back to the original value when I've used an auto beat loop in conjunction with slip mode (as a roll effect instead) - the only way I can seem to avoid it is by switching master decks all the time which is pretty annoying - is there a way I can stop this happening ? (It keeps happening mid-mix which is not good!)

cheers

adam