After command "Find Cover" the AI will never be hiding inside buildings. Unfortunatelly this command is useless and requires significant editing. In this case, at least a most units should take cover inside buildings (if the any building is nearby)
But no one unit will not do this.
//Example://
https://www.youtube.com/watch?v=VOcctYUZCe8&feature=youtu.be
@BIS, teach the AI use the "Find Cover" command is more effectively.