AI not reacting to fire, even if I'm very close.

Here's what happened:
I was playing the single player mission "Resurgent West" of the "Win" campaign.

My objective was to secure some defenses located east of Neochori city.
I've approached from the south-west climbing up the little hill with the AA tank on it.
Then I see three enemies, I start shooting but they don't react at all.
I kill two of them (then the autosave starts since the game thought I had successfully secured the place completing the objective), but there is still another AI alive.
I start recording, I shoot and the AI doesn't react. Just waits to be killed, and that's what happens!

I've attached also the .rpt file!

Here's the video but unluckily, due to the autosave, I've recorded only the death of the last enemy:
http://youtu.be/2R4Lluy1Azw

If you need another video, I'll try playing again the mission with the same approach!

{F25764}