Ever since Patch #7 pathfinding has issues with terrain elevation; often resulting in characters either sinking into the terrain or falling through the terrain or levitating and then falling while trying to descend.
*As can be seen in this preview; the pathfinding due to terrain elevation often acts weird and thus causes the issues mentioned above.
Here are just a few realtime examples of the buggy pathfinding:
Hag's Lair - party members sinking into the ground after climbing (00:07). Afterwards they also keep dropping out of air while descending due to poor elevation adjustment (00:17).
Reithwin Town - character falls through terrain because the game doesn't adjust the character's elevation properly after climbing ladders (00:34)
Baldur's Gate - as presented above sometimes even the tiniest elevation confuses pathfinding by showing nonexistent sudden drops (00:44)