Issue between Blender Source tools and Blender MMD tools

Blender Source Tools 2.7.1 and Sugiany’s Blender MMD tools.

When porting MMD models to Source Engine using the DMX method, sometimes they work perfectly, but sometimes the textures get completely messed up when importing the exported DMX back in.

My usual procedure in Blender is to import a PMX I like (and translated sufficiently), activate GLSL to preview textures, then simplify the material listings. Then, I export a DMX from the mesh, and start actually adapting the model to Source. I got much of it down, rigging isn’t a problem.

The main problem that I seem to randomly get is that for some reason, some DMX exports of some MMD models get artifacts and messed up UVs on certain parts of the mesh but not others. Even turning off Auto Smooth doesn’t fix it. I had to abandon some of my projects for that reason.

Funny thing is, exporting to SMD doesn’t cause those problems (though they have their own set of problems that I won’t get into). Even exporting a DMX out of the SMD won’t cause such artifacting. What may be going on?