To sneak attack, you have to either 1: Have an ally next adjacent to the target creature; or 2: Have advantage on your attack, AND not have disadvantage on the attack.
I don't think the pictured scenario is a bug, I think you have advantage on the attack from being a sneaky bastard, but also disadvantage on the attack -- presumably from the enemy being in darkness or something. If that is true, you wouldn't be able to make sneak attack damage. I think it's working like it's supposed to.
Agree. Although I think some sources of disadvantage are weird as of right now. I am pretty sure that I had cases where the enemy was "in the shadows" but my PC has darkvision, so this should not have been a problem. My guess is Larian imposes disadvantage in dim light for attack rolls, but it only should be for perception checks.
