I rotate both arms using the Mirror option, then I press "Insert Keyframe" -> "All Channels".
One arm snaps back to the previous position. It seems to me that Blender ignores the "Mirror" option and only keyframes the one arm which I have actually rotated instead of both.
Am I right?
I have recorded a video of this strange behaviour here.
Can anybody help?
Edit: I have filed a bug report here because it seems so strange. If I select both bones (left and right bone) manually and rotate, it persists, so I'm really baffled what goes on here.