This was unfortunately also an issue in Divinity Original Sin 2, but at least there the player had Telekinesis to circumvent this terrible shortcoming with pathfinding.
Fear not, for while telekinesis is a level 5 spell in BG3, we also have this thing called mage hand.
It's obviously not a fix, but for some reason, casting mage hand and ordering it to throw an item to an easily reachable place works, where trying to do the same with your player character would just give the error.
