For most things, when you highlight a target to attack and it shows you a percentage, on the left, it should also have a little window that will tell you whether advantage or disadvantage are in play, and what those factors are coming from - I say most, because the game is a bit spotty with actually telling you why you have Advantage or Disadvantage at the moment, but at the very least it does tell you *when * they are in effect. I couldn't say for your exact case, but keep an eye on that and see it it feels like it's making many more sense for you.
