It is the mesh from SimNIBS, that @YRW posted on github.
@Francois did we fixed this error with the last discussion with iso2mesh dev team?
Yes, I believe it was fixed.
At least it works now on my Win10 computer:
@YRW
Takfarinas is right, you haven't gone through the step of remeshing the SimNIBS mesh.
It is clearly stated in the tutorial that in case of problem with MEG and SimNIBS meshes with air cavities, you must remesh the layers.
Please follow this section step by step:
https://neuroimage.usc.edu/brainstorm/Tutorials/FemMedianNerve#Remesh_with_Iso2mesh
If you have issues with iso2mesh, please post full error messages and screen captures.