Sometimes "A" side doesn't play in Rekordbox

I've just bought a Pioneer DDJ-RR and have the newest version of Rekordbox.  Often I can't play the "A" side in Rekordbox or on my DDJ-RR, but the "B" side is just fine.  If I quit out of Rekordbox and go back in, the problem is resolved.  But it happens more than once in a day.  Is there something I can do to resolve this without having to quit and go back in every time?