Not getting XP for kills

[MercyLost]

Whenever I kill something from high up with a thrown weapon, it doesn't reward XP.
Started after I got the Tavern Brawler feat.

[Calculus]

Did you use any skill checks to avoid the fight?
If yes, then game rewards you with the same amount of xp as you just killed them.

That said there is an exploit, unless it was patched:
if you save and load the game after convincing enemies to not attack you, their xp pool resets, so you can double your experience gain, now if you knock them unconcious, then you save and load and kill them, you will get xp again, actually tripling the xp gain