The Ti'Tsang wasn't in a ECM hex but when a ASF was striking it, the Ti'tsang got the ECM bonus anyway. The ECM check is probably checking for the ASF's ending hex instead of the target's hex, or checking for weapons fire from the ending hex to the target hex.
I have a saved game from a newer version for reproducing this bug. While I understand that conceptualy it feels like this is the way things should work, it's not clear from the rules that this is how it should work (ie, the Striking rules give you the impression that the ASF is making the attack as if it were in the hex of the attacker, but it never says that). I'm working on getting a rules clarification to make it explicit.
Ok, I got a rules update from Xotl:
Total Warfare, p. 238
So with the new rules, the Aero wouldn't be under the effects of the ECM, unless it was at NoE (and hence couldn't make a strike attack).
Last edit: Nicholas Walczak 2016-01-26