There’s a lot of variables. If the bandit is hot and close, there’s no reason why it should drop UNLESS, the bandit is below you and your altitude is fairly low. Make sure he isn’t notching as well. Assuming you are doing that, then all I can say is I feel ya.
ive had aim-7s fly off into the sunset wiyh the “lost” notification on my HUD seconds after firing. But I’ve posted tracks before long ago, raised the issue (as have others) and have been assured all is WAD. So I have to assume it is.
but like you, I find it hard to believe that the F-18C radar would lose STT lock on a hot (or flanking frankly) target less than 10 miles away.
all of that said, performance is MUCH better than in times past. Maybe I’m paying more attention now since aim-120s aren’t working well (pending completion of the new guidance stuff)