If I had to guess, Id say your 37mm's (I assume you wouldn't shoot just 2 rounds at a T-34 from a wirblewind or M16, so that leaves the Ostwind) just missed. The accuracy on the 37mm isn't stellar, even at only a couple hundred yards (it relys on more damage per shell, rather than number of hits), and out at 1000yds or so, I'd say its safer to bet that you miss than it is to bet that you hit with the first two shots.
But aside from that, I haven't heard any complaints about aircraft mounted 37mm's having ghost-shell problems. Theres no reason that the modeling for the 37mm on the Ostwind should be fundamentally different from the modeling for the 37mm on the P-39 or Yak-9T.