This is a bit of a specific case, but I have some avatars that I actually don't want the spine to bend on. My problem comes when I limit the spine rotation in Unity in the avatar config, my hip is always rotating with my tracker, However on certain avatars I don't want that to be the case due to their body shape.

When I limit the spine rotation, the head desyncs from my real head in Lock Head, Lock hip and lock both mode and the entire spine bends downwards because the hip tracker rotation is always enforced.

I feel like if there's a rotation limit on the avatar rig settings, it should possibly keep your head in place and make the spine not rotate on the up/down axis in this case?

Attached below are the rig muscle settings in Unity combined with how it looks like in-game. I'm doing the exact same pose here IRL in both screenshots.