I had also a classic skrimish game when I saw an upgrated Misty Mountains army from a Brutal AI standing still and doing nothing during an age, allowing my team to gather enough money to give us an easy win some kind of which we wouldn't have in the previous version.
I was the first attacked. My door was closed but at a moment I opened my gate, and the AI still didn't move to try and attack me. He didn't attack my partner either or only with lone units, but the major part of this army in the screenshot stayed motionless, bored by their job.
When he launched some attack from this big clutch in this screenshot, it was only 1 or 2 units instead of all this army at once which could have been more effective.
This passivity of the AI seems to be a recurrent problem in Edain 4.8.
