mobs fall under the world when chasing you into water

[Chortles Snort|eS]

just experienced this bug as well
can reproduce if requested

[Izmael]

Bump

[Ennewi]

Similarly, aquatic mobs will beach themselves on dry land when aggro'd, being above water but with their movements restricted, making them vulnerable to spells and ranged attacks. However, these same mobs have no issue with "man-made" structures; the piranhas in Nektulos regularly pass over the bridge, causing the guards to attack them.

[Evilmorty]

I've had a problem with mobs pathing into the water and getting the "cannot see mob" spell interrupt while trying to cast from both land and below the water, and my pet was able to follow them but not attack. The mob appears to be continuously falling from the sky into the water, similar to falling through the world.