The new structures added (originally from JBAD) in the CUP update, or at least the large brown/green camo building, possibly a barracks/military office, do not have any AI garrison or AI move points, so they can't be used by AI.
Manually placing AI inside the structure can work, but the glass in the building apparently is 'solid' to AI vision- they can hear targets on the other side of the glass- they call out and follow with their aim, but they only fire if the glass is broken, giving them a clear 'view' of the target.
AI inside or outside the structure will not fire on each other if there is glass in the way- once broken, they fire as normal.
This was reproduce able.
Steps- Find large brown/green camo structure, example Balota Airfield, Cherno or Takistan North airfield.
Place AI inside (via editor, as there are no garrison/move points so AI will not man the structure themselves.
Place AI outside, facing glass between the two.
AI on interior should be in safe/non-combat and will not see the unit outside, or track him without firing, Once glass is broken the AI will engage each other as normal.