Disclaimer: This is in Blender 2.8
I made half an armature with constraints (IK and/or Copy Rotation).
All modifiers applied on mesh.
Happens with Armature → symmetrize menu
Happens with Shift-D Duplicate → scale -1 on X
When trying to duplicate the bones to the other half bones rotated strangely.
1 - Bone roll corrected
2 - Only visible when “posed” is turned on in pose mode, or in object mode
3 - Rest mode returns the bones to proper position
4 - Edit mode sees bones in proper position
5 - Alt-R or resetting pose returns bones to wrong position
6 - Copy/paste pose does not work
I tried to recreate it but no luck, so I can’t call it a bug yet.
Anyone else had a similar problem, has a solution?
Image follows. It looks like it is scaled on y, but it is not. It is rotated by about -120 degrees: