Articulation Bodies are moving in local space since 2021.3.9

[Qleenie]

Hi,

just updated from 2021.3.7 to 2021.3.9 and since the update I am observing a strange behavior:
Articulation Bodies (with Sperical Joints) are slowly, but constantly moving in Y direction relative to their parent. This ONLY happens if there are child objects with mesh colliders attached to the Articulation Body. Disabling and enabling the Articulation Body resets to correct position configured in anchor.
This is a severe bug in my case. Will try to build a repro project asap.

[Qleenie]

@Qleenie

Hi,

just updated from 2021.3.7 to 2021.3.9 and since the update I am observing a strange behavior:
Articulation Bodies (with Sperical Joints) are slowly, but constantly moving in Y direction relative to their parent. This ONLY happens if there are child objects with mesh colliders attached to the Articulation Body. Disabling and enabling the Articulation Body resets to correct position configured in anchor.
This is a severe bug in my case. Will try to build a repro project asap.

As in most of the cases, it’s the users fault I introduced a script at the same time, which caches local rotation of a transform, then changes it, and then set it back to cached value, all in one step. Somehow, this seems to change something I was not aware of, either on the Transform, or the attached Articulation Body. It’s probably not a bug on Unity’s end, but wrong usage.