Actually, think it's a bug. I have had this happen to me MANY times, but never thought much of it, UNTIL me and 4-5 squadmates were doing a fighter sweep, and within say 1-2min, four of us had this problem. THEN again on our next fighter sweet. 1st was in FW190D, 2nd in Spit 9's. So wasn't just me, and if multiple guys having same problem at same time, I would say Bug.
Needs looking into.