I've now seen the problem at cama, an oval room, no line of sight issues there. killing some of the adds, pets get into the described toggling mode. Both pets reply attacking, but only one moves to the target and attacks, attack macro again either leaves them doing the same, or switches them. At times I hit the macro up to 3 times, and dog kept attacking, while widowmaker stood by me, both replying attacking, then on 4th try, dog came back, and widowmaker attacked. At this point each time macro is hit, pets switch places.