Hey...
I just got home from work...
I'm presently looking at your model...
I see you have only .dds textures... Therefore, the alpha channels can-not be the problem.
But... I see that all four textures are identical.
So... I have created a new file and I marked three of the textures as "Shared" with the first.
That way the model file size is reduced from 5.8 to 1.7 meg... You should do the same!
I will now add both models to my present project for a test...
More comments to come...