Here are two missions to test.
One is with Hot Aspect of an SU24. Shooting it down is no problem. PDI mode stays stable.
The other one is the same but with cold aspect, the SU24 flying away from you. As soon as you launch a Sparrow, the Radar goes into PDI and looses track soon after. This happens every single time, I have tested it 20+ times with the same result.
At the current state, the AIM7 is pretty much unusable in the hornet.
F18 AIM7 Cold.miz
F18 AIM7 Hot.miz