As noted on the ResetERA forums, a post by jamesdickinson963 on the ACM Overhaul ModDB page traced the problem to a spelling error in a single line of code within the games ini file. The code shown below should has "teather" instead of the proper "tether". This simple mistake in theory, results in the "zone tether" failing to load the AI parameters attached to the broken bit of code.
Original Code: ClassRemapping=PecanGame.PecanSeqAct_AttachXenoToTether -> PecanGame.PecanSeqAct_AttachPawnToTeather
Fixed Code: ClassRemapping=PecanGame.PecanSeqAct_AttachXenoToTether -> PecanGame.PecanSeqAct_AttachPawnToTether
Once the spelling mistake has been fixed it does seem to improve the game's AI, as corroborated by PCGamer's short video clips. In terms of improvements, the Xenomorphs tend to behave in a more aggressive manor, taking less time to attack the player. They also flank, leap and chase more often. Moments where the AI feels lost or confused still happen but the frequency is reduced.
If you have Aliens: Colonial Marines installed give the fix a try and let us know if you see a difference.
To change the code go to: My DocumentsMy GamesAliens Colonial MarinesPecanGameConfigPecanEngine.ini
Source : TechPowerUp