KH-38MT targeting issue?

Hello! I've just unlocked the KH-38MT for the SU-25SM3, and I've been trying it out in Air RB. I know it's an AGM, but it's maneuverable enough to actually score A2A kills - or so I've been told. Despite launching on distracted non-maneuvering enemies and seeing the missile follow a perfect trajectory, I've been seeing a lot of extremely close misses. Any idea on why this would happen? I tried it out in the testing ground and it could easily hit the flying MiG-15s, yet in battle it can barely hit an F-104 flying perfectly straight.