<< What PNG file would you expect to be generated from MoI's OBJ export? 
Colors Style of works used during the modelisation inside MOi... 
like following (not exactly the same because i have not more the modified object (at ends' arm/ hands) 
 
But i must continue to investigate!  
MagicaVoxel create 3 files OBJ, Mtl and PNG file : this last one is one horizontal line of the 256 or less colors used !
 
It's this png file that i have artificially add inside the 2 files created by MOi and magically object will have colors! 
Mixamo ask a zip file of these 3 files!
 
Here result with the artificially Moi 3 Files zipped :)
  
:)
   
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