Reply To: mirror poses / paste flipped issue in 2.93.4
So I solved it (second pic) by deleting a bunch of key channels, but I have no idea why this worked, or what was going wrong in the first place, or what I need to do in the future to avoid this. (The first pic is a shot of what happened when I was part way through deleting various channels — the type of error seemed to change, which is why I included it.)