Ok Zbrush is doing that thing again where I do a completely mundane task that I’ve done hundreds of times before but it behaves COMPLETELY differently.
I exported a lvl 2 mesh from a zTool for rigging in maya, I had to resize and reposition it in maya, and now I want to update the mesh in zbrush to be in the same place for the purpose of sculpting blendShapes.
So I tried to import the same OBJ I exported out back into the lvl 2 of this zTool, and it explodes.
I checked all my settings and couldn’t find any faults so I decide to just export the lvl 2 again, bring it into maya, export it right out without touching it and re-importing it into zbrush, to test if this works.
And for some reason now when I import in Zbrush it leaves me with my only the highest level in that zTool, all the other level just disappears.
I found out that if I scale or move the obj in maya before re-importing, it will scale/move the zTool in zbrush, but it still deletes all but the highest level mesh/
Please help, about to rip my remaining hair out.
EDIT: after further testing, there’s definitely something funky going on with this tool, I tried the same thing with another tool and it works fine, but this one… it’s not even letting me reconstruct subD after I deleted all the levels but the highest 1. 
EDIT2: Ok it’s only doing this to ztools which were generated from the zsphere retopology / adaptive skin tool.