Sometimes I have a horrible suspicion that pathfinding is not the same even between TB vs RTwP, especially in Wrath where amount of TB specific movement bugs and bugfixes was piling over the months like crazy. For example, that impassable door bug from latest patches.
Please, don't ask for proofs...(
And pathfinding is indeed supposed to work differently in cases when you cross the space taken up by some creature:
Friend: You can move through a square occupied by a friendly character, unless you are charging. When you move through a square occupied by a friendly character, that character doesn't provide you with cover.
Opponent: You can't move through a square occupied by an opponent unless the opponent is helpless. You can move through a square occupied by a helpless opponent without
Penalty. Some creatures, particularly very large ones, may present an obstacle even when helpless. In such cases, each square you move through counts as 2 squares.
Ending Your Movement: You can't end your
Movement in the same square as another
Creature unless it is helpless.
And from what I saw, Owlcat tried to implement those rules, but the whole thing is beyond messed up. Plus, there is no restrictions outside the combat, but when combat starts and everyone in the same space they get stuck.