I downloaded some 3D models online. 1 is a hat and the texture loads in Blender when I put the viewport in texture mode but the other one not.
Here are screenshots of hat folder and tank folder. Screenshot of blender.
You’re importing as what? .OBJ?
If so, you might have noticed that the tank folder is missing a .MTL file. That would contain the material definitions and the references to the texture files. Since it is not there, Blender has nothing to import material wise.