So the behaviour is seen due to hinge joints getting enabled and setting up their axis information on a rigidbody that may be disabled. This results in the hinge joint attaching itself to the world, as if the rigidbody was not set. The problem arises that when the Rigidbody eventually gets enabled, there is no callback, because a Rigidbody does not store any reference to joints that might have it defined as a connected body, so there is no callback for the Hinge joint to update its axis information. A very simple fix in this case is to just make sure the Hinge joint gets enabled AFTER the rigidbody is already active OR disable/reenable it again once the Rigidbody is active. Fixing this bug would require us to add a lot of cross links between rigid bodies and articulation bodies with joints, which has a high risk of introducing more issues. Since this bug has an easy workaround we will not be fixing it as of now.