NPC Humanoids dont walk on the ground after BodyVelocity

Reproduction Steps
After applying a BodyVelocity to the HumanoidRootPart of an NPC, it will sometimes not land back on the ground, instead it will land in the air without falling back to the ground.

This behavior began suddenly (about 1.5 weeks ago) in my game after several months without issue. The code involving the NPC movement had not been modified when this change began.

The BodyVelocity is part of a knockback effect applied while fighting the NPCs. I simply instance a fresh BodyVelocity, set its values, parent it to the targets HumanoidRootPart, then quickly destroy it.

In the video below, you can see this happening from both the client perspective and the server perspective. If you drag the NPC it will fall back to the ground.

Expected Behavior
I expect the humanoids to fall back to the ground.

Actual Behavior
they walk around in the air, presumably thinking they are on the ground.

no workarounds

Issue Area: Engine
Impact: Very High
Frequency: Often
Date First Experienced: 2021-06-26 00:06:00 (-07:00)


I’ve noticed something similar in my game. Our NPCs will randomly get in the air somehow and without there being anything for them to stand on they will just walk in the air and stand there like nothing is happening.

Hi thanks for the report! Could you send me an isolated place file that will reproduce your bug?

I have also had this bug when I tried to create my custom Mario movement

i can send you a copy of my game?

Hello! Is this issue this occurring? If yes, can you please send a small repro file to Logs / crash dumps / other bug files - DevForum | Roblox and notify me so that I can forward it to engineering? Thanks!