I seen something similiar last night. I finally got on a six of a pony and was tearing him up, and then *poof*, he was gone. No kill, no proxy, nothing. Will have to look to see if I got on film. I know a few others have seen this issue in the squad since the patch. 
The other plane discoed before the host could have the kill registered which is why there wasn't a credit recorded for the kill. It has nothing to do with the recent patch, it's just one of those Internet lag things.
This is the reason why the OP didn't get credit for the drones after he killed the manned bomber just prior to the player being discoed. This also explains why sometimes you blow someone up and didn't get immediate credit and then a few minutes later you get a delayed kill message.
However, if the player was to Alt+F4 out instead of being discoed, you would then get credit from the kill via a proxy (or if you damaged the plane prior to the player alt+f4'd out) since if you Alt+F4 out of the game it counts the flight as a crash/death.
ack-ack