Thanks for reporting and sorry for the trouble!
We are aware of this issue, it is related to bone rotation crossing the 360 to 0 degree border:
[unity] 2D Hinge Chain rotation issue (repro project) · #1636
SoulGame wrotethe hero in the example doesn't have those split FlippedX setup
This example scene is using the 3D physics counterparts (normal HingeJoints instead of HingeJoint2D, created via Create 3D Hinge Chain), which allows for simply rotating the root by 180 degrees and is in general more robust. Unfortunately the Box2D 2D physics integration in Unity is not respecting negative scale or rotation by 180 degrees appropriately. This led to the complicated setup in the first place.
So your options could be:
a) to use 3D hinge chains,
b) to change rotation of the problematic bone in setup pose by a +180 degree offset (with attachment images etc not being affected),
c) wait for the bugfix.
Sorry for my weird goblin accent :nerd:
😃 I am no med. doctor, but I would declare your voice as perfectly normal. :nerd:
