Switching LinearVelocity.VelocityConstraintMode freezes replication

[nezuo]

If you switch the VelocityConstraintMode of a LinearVelocity or enable a LinearVelocity with a different constraint mode the part will freeze on the client temporarily.

Here’s a video that shows the behavior:

linear-velocity-bug.mp4

And here’s the place file used in the video:
linear-velocity-repro.rbxl (37.2 KB)

[DrCherenkov]

After testing it a bit, I believe this is essentially the same issue reported here:

LinearVelocity has an inherent replication delay when created on the server and viewed on the client

I can confirm this issue also occurs with AlignPosition, which makes the switch from the deprecated BodyMovers basically impossible due to the very visible replication delay. When the knockback is applied, a neon blue box is spawned at the damaged character for a split second: This was the code used to implement the above knockback behavior:

Code

export type KnockbackData = { Direction: Vector3, Distance: number, Time: number, IgnoreGravity: boolean, } function Module.Knockback…

The good news is that I’ve implemented a fix but it will take some time to roll it out due to the nature of the change. I’ll report back once the fix is live.

[DrCherenkov]

This issue can be fixed by enabling the Workspace property Workspace. MoverConstraintRootBehavior. This property is part of a three phase rollout with more details found here: Improved Mover Constraints: Enhancing Stability and Network Ownership

Let me know if Enabling the new property fixes the issue for you. Thanks.