No - I'm yet to use meshmixer, I hadn't needed to look elsewhere as the Prusa version of Slic3r has been working really well. Its weird, Cura sees it fine and from what I can see when importing the STL in Fusion360 it's ok as well, only thing I can think of is a detached vertice, but that seems unlikely given it works fine in other programs. I don't know why any of the sensor versions work fine but the non sensor version doesn't. Confused as well!!