The UpperArm and Hand parts have extremely large mass which can cause game-breaking behavior when players wear it (such as flinging into the void, or preventing the character from rotating).
I imagine this has something do with floating point error since the mesh shape seems to very small. Maybe you guys should be sanity checking a mesh’s mass values to make sure they never go above the volume of the bounding box?
Examples of game breaking behavior:
- Flinging character into the void when applied via Humanoid:ApplyDescription()
- Preventing character rotation (and flinging into the void when in first person) when applied via Humanoid:ApplyDescription()
- Applying extreme forces to other unanchored parts when the character walks into them (see Maelstronomer’s reply for an example)
- Flinging character into the void when it is ragdolling with BallSocketConstraints
