So many pieces of terrain make the indicator completely invisible whether they be surfaces you've created or set pieces. It gets really annoying really fast having to rely on estimation as to what counts as the "back" of an enemy. The only reliable way to get behind an enemy is to use vault but at the same time it's really glitchy sometimes in places where the enemy has their back to a wall especially. It places you a bit too close to the target resulting in you having to move out of the back-zone to attack. The best way to work around the glitchiness of vault is to have "the pawn" talent and walk around to the back. This was just a bit frustrating throughout my 100+ hours (get a life me) of gameplay.