Maulers are going to be "fixed" in the next update. pathfinding has been flaky from the start and it seems that units like to go trough from high ground. This can be easily replicated in the small 2 player Fringe where units decide to go over the small hills on the sides of the map. Targeting has never really worked and it is kind of a crapshoot atm, usually buildings will get targeted but there are times when they cant be targeted for some reason.  I actually lost a ranked match because my units refused to kill off an engineer who was building turrets on the edge of my base.  

What I ahve found out too is that when you give your units a direct attack order, they sometimes just stop attacking completely and sit there soaking up fire from the enemies untill you give them different order.