From some brief testing it appears that if an aircraft carrying Kh31PD faces Soviet opposition as ground targets in Air RB, the missile cannot acquire the opposing radar returns and will only track Western radar emissions. This is quite problematic, as these munitions cannot pierce air base air defences from a single platform and thus are relegated to midfield AA targets for the most part.
The fact that the Russians end up going against Russian ground targets is a bit silly in and of itself, but it is now proving mechanically detrimental. Su 30 / Su 34 are the primary examples of launch platforms that cannot engage midfield air defences due to this limitation.
I will continue to try to validate this behaviour further, and check the other Soviet ARMs for the same behaviour.
I have not experienced this with NATO munitions, even when facing western opposition. If this behaviour does exist with western munitions, feel free to respond. Better to get information across the board.