Infantry AI are mainly unresponsive when handled by server. They will not move or change stance, they will engage visible targets, but will not change stance to hold / aim their weapon. (See Additional information for footage as it's difficult to explain exactly.)
The issue does not carry over to units placed in Zeus (but does still affect units spawned via sqf scripts). The issue also seems to not affect vehicles or passengers, vehicles will still move and passengers that have dismounted will act perfectly normal.