Bone Turns Orange And Auto IK Doesn't Work The model's left leg is perfectly fine. I can select the lower leg and with G, move the leg with auto IK. For some reason, when moving any bone on the body, the right leg's upper bone turns orange. The right leg will not budge when using auto IK, but moves just fine with normal rotation and positioning.

I'm very confused. The armature has no constraints on it. The bone just turns orange and won't move with auto IK.
I've stumbled upon this question myself and believe that this is an issues regarding X-Axis mirror and Auto-IK working together.
To reproduce the issue,

In pose mode, turn X-Axis mirror and Auto-IK on together.
Move a bone that is properly mirrored, the Auto-IK and X-Axis mirror should work fine, result in the mirrored bone moving accordingly.
Turn off X-Axis mirror, then try moving another bone, the &quot;mirrored&quot; bone you just moved (the one you didn't directly grab) will appear orange and attempt to stay in its place, result in certain bones locked down.


So to clear this situation, you can simply &quot;turn X-Axis mirror and Auto-IK on together again&quot; and &quot;move a bone that is NOT properly mirrored (like the head or any other bone in the center).&quot; Then you should be safe to turn your X-Axis mirror option off!