Only way I've found to know you can sneak attack is by hovering over the enemy and making sure you have advantage (getting behind or above is generally guaranteed). However, I don't know if having an advantage and a disadvantage cancel out the advantage needed to trigger the extra dmg from the sneak attack.
Weird bug I noticed in the latest version is sometimes you must hover over the enemy's feet or lower body to have advantage applied (and increase hit chance). Hovering above a certain point on the enemy has a lower chance to hit and no advantage. I've mainly noticed this with ranged attacks. Happens a lot.
