I made this katana model in studio and imported it into blender where I used ROBLOX Material Essentials from blendswap to give it the roblox textures and when I export it back into roblox as a FBX file I get no textures at all I have tried so many video none have helped.
When you export a model (mesh) from Studio and you import it into Blender, you also will notice that vertex points are split. The base color texture map is usually in the same directory on your computer when downloading the .obj file.
you just need to make sure that the texture map is also assigned to the base color slot of your blender material.
If you share your Blender file or the model you downloaded, I can walk you through the process.