**System Information**
Operating system: Linux (Debian bullseye)
Graphics card: Nvidia Geforce GTX 1070
**Blender Version**
Broken: current master (2.83.10)
Worked: I didn't bother to test...
**Short description of error**
When using X-Mirror in Pose Mode of an armature with auto keying enabled only the modified
bone will get a keyframe inserted. The mirrored Bone will be affected but will not get a keyframe.
**Exact steps for others to reproduce the error**
Add an armature with some mirrored bones (for testing get one from the Rigify Addon) and enable x-mirror and auto keying.
Then just test it... pretty straight forward.