I’ve had this problem ever since I installed Z4, but I’ve just been working around it up till now.
So yeah… I hit the GoZ button, it sends it to modo correctly, but everything is upside down. I thought GoZ was supposed to know the export flipping direction for each package? How can I fix this?
buuuuump… 
I’ve had the same problem. It was SUPER annoying. I think what fixes this is a preference setting box which you can enable flipY or something. But not sure if it fixes it.
…Another issue i am having lately is that after i edit the mesh in Modo, and goz it back into ZBrush, and then i opt to NOT transfer the hi-res details, it makes the mesh arbitrarily larger, like it automatically “unifies” the mesh.
Then I need to manually re-position and re-scale the mesh back to where it was before, which obviously makes it less accurate…