Hum, still no mean to reproduce that. I put RHS tanks, some infantries, one show/hide module to hide tanks, another one to show them, with a trigger radio Alpha. They starts inbound to waypoint when shown, they " knowsabout " enemies very quickly.. and fire shells on enemy tanks...
On the other hand, I'm on Altis airport, no place to hide.
So, you can have some broken behaviors with the way you start the mission (tanks are only hidden?)
Or a so heavy scenario, that you spend a lot of time to gain sufficient enemy tank knowledge.
You can speed up that, (and it's important after disabled simulation), with a little code along with the trigger activation:
for "_i" from 0 to count allGroups - 1 do {
_grp = allGroups select _i;
{_grp reveal [_x,4]} forEach (vehicles select {_x isKindOf "tank"})
};
It's not optimized as this code recovers all the existing groups, but you can name tanks and use the code just for their groups.