Well, it just happed to me. I was first to reserve the afternoon jumpeat from MEM to DFW on Aug 7th - got it two weeks prior. Today I got a notification that I was bumped by a higher priority. I call Jumpseats and they said there are only 3 seats on the plane. 1 is an LCA, one is a pending cockpit captain's permission and the last is a crewmember who reserved it after me, but used business. The lady said she new about the problem, but there was nothing they could do about it and it was an ACP problem and they can't get a handle on it.