Yes, @TrippyLighting, this is, well, not exactly "correct", but as on purpose. The problem is the nature of the mirror. A Joint Origin is really just a coordinate system. If you mirror a coordinate system, you end up with a left-handed coordinate system, and most CAD software (including Fusion) cannot deal with a left-handed CS. We could have copied a right-handed CS at the same place, but it would have been backward. This is also why we don't mirror joints, since they are CS-based as well.
It's a bit of a research project at the moment. It's not clear to me whether or when we will implement something like this.
Jeff
Jeff Strater
Engineering Director