This might not be 'AI Control' issue, just mission script, however since I'm not sure, wider category might be better.

Im not quite sure now if this spans over two missions in chapter 3 or not.
However AI LAVs tend to run over troops.
Case:

1. In mission in which kerry assults enemy positions along LAVs( iirc this is the first mission with LAVs)
2. When kerry can call LAVs to eradicate enemy LAVs - in this mission HALO is hot down and player has to engage AA afterwards.