Excellent work, Stu. I shall perform some experiments and report back, post haste!
[EDIT] Hmm... yea verily, it seems that heat seekers won't track targets with 'hidden from sensors' ticked. Which is annoying, since that's the entire point of the TempestS... Otherwise, they work fine.
So... why won't heat seekers track hidden enemies? I tried it with the Rockeye, and the same thing happened... very odd.
[EDIT] More experimenting... this time attacking a hidden-from-sensors cruiser. Again, the heat seekers won't home in on the part of the cruiser I point them at, as I had expected. Therefore, I need a way to have heat seekers simply lock on to and track which ever target is nearest, without that target having been locked by the player. Presumably, this is a source code job...