I’m working on a walk cycle but for some reason when I copy a pose to buffer then paste as mirrored it totally messes up the rig. In my attachments f20 is my original pose…F60 is that same pose copied then pasted as mirrored. The spine bones don’t match up, a foot drops way low, and the hands look they go back to rested position. I’ve set a rest pose, applied position, scale, and rotations and can’t think of anything that would cause this issue.
This has been happening to me too, when there’s some rotation in the y-axis of some bones.
The only things I can suggest that you check for are to be sure the 3D cursor is centered correctly, and setting the 3D cursor as your pivot point. If that doesn’t fix it, then I’m not sure what’s going on.