noticed the mtl file is probably corrupted when i export a file.

one voxel on each layer is all black and cant be changed when exported and imported to a 3d modeller.

Hey there, 

This sounds like a pretty serious issue. Would you be able to email me at incinious@gmail.com with screenshots of the exported model, as well as screenshots of what it looks like in-editor. Additionally attaching the exported obj and mtl files would be helpful. 

I will try and fix it as soon as possible. 

Thanks 

Sent email with all files.