When a player is standing on an object affected by physics that is unanchored → anchored → unanchored it causes the player’s relative physics replication to desync. I believe it is related to the Characters on moving platforms feature introduced in 2018. I have attached a place file that should allow for simple reproduction when following the steps.
Press Play
Stand on the “broken elevator” and activate the prompt
Wait until the elevator reaches the top
Press the prompt at the top
Wait until the elevator reaches the bottom and active the prompt
The elevator should take significantly longer to reach the top.
The elevator seems to take longer to reach the top due to the fact that your character is colliding with the platform / is inside of it. This also causes some odd visual replication issues on other players screens where you may be seen as floating or inside of the platform. If you are to step off the platform or jump, the issue resolves itself right away, the issue will reoccur if it anchors and unanchors while you are standing on the object. Elevator.rbxl (71.4 KB)
Expected behavior
The elevator should preform the same as the working elevator that is also provided in the same place file, it should properly handle the relative replication of the physics that the character has regardless of if it was unanchored.
I am taking a look at this now. I am able to reproduce the issue and agree that something does seem to be going wrong here. Do you know if this behavior is limited to Humanoids or can you see it in other situations, like with a custom character controller?
The new character controllers do not behave well at all on elevators (and to be honest in many situations). They jitter constantly ontop of the elevator and clip into it often (similar to the issue experienced on humanoids after the elevator is unanchored). I have attached a place that is using the Physics Controller setup provided in Releasing Character Physics Controllers.
This seems to be fixed, however there is still a good amount of jitter/lag when standing on the platform as it un-anchors, which is likely a separate issue. Thank you for resolving this.
Thank you for the update. I deployed the fix a couple weeks ago but forgot to circle back after the fix was live. I agree the lag/jitter sounds like a separate issue. If you haven’t already, it might be worth testing things with Workspace.ImprovedPhysicsReplication set to enabled to see if that helps. Thanks.
Workspace.ImprovedPhysicsReplication does not resolve the issue, but I think with how anchoring and unanchoring works in engine, the difference between the two elevators is to be somewhat expected. But the same repro place in this thread can be used to see the difference in case it is unexpected.
