Loaded scenario into patched version of game, tanks happily fire HEAT ammo at the hinds, until they evade - when only the AAMG can engage. Repeated test in the issued CD exe, with same results.
No problem with firing tank main gun at helos - armoured or vanilla.
Yes - I had not got the 1.0DL version loaded in my scratchpad test folder, looks like something that changed between 1.0 and the CD version though I have no recollection of doing it !