Alright! So I made this RPG model and tried to import it into Roblox Studio, And the textures seem to bug out and show up as one color. This is what it looks like in Blender: 
And this is what it looks like in Roblox Studio:
They are separate meshes with separate textures, Yet it still glitches out.
UV and Textures:
Alright!
Here is the texture and UV for the Launcher (2000x2000):
Here is the texture and UV for the Rocket (1080x1080):
are you sure it’s not multiple images in blender? if they are the won’t show up correctly. You need to bake them
I already tried uploaded the textures individually, But still got the same results.
I’ve also used this method for other meshes that I made and it worked just fine.
With this info I’m sure we’ll be able to narrow down the solution 
Alright!
Here is the texture and UV for the Launcher (2000x2000):
Here is the texture and UV for the Rocket (1080x1080):
It looks like Roblox’s image compression is wrecking your texture because you didn’t unwrap it well. You need to properly UV unwrap the launcher (and honestly the rocket could unwrapped better too). Make sure you mark your seams and unwrap to maximize texture space. Watch some tutorials on how, there’s dozens that explain it better than we can
I don’t want the shark mouth to cover the whole rocket
you can split the faces in the uv editor by pressing Y. Make sure everything fits in the uv layout
What about the launcher? It fits in the layout
Nevermind, I fixed it. All I had to do was not export them as obj groups then limit it to Selection Only and, Export them individually instead of an obj group.
Here is the end result:
It looks good, but you should still fix your UV and texture, you have a lot of redundant space that would be better if used, and you can combine two textures into one to improve game performance. If you aren’t filling up your UV space, it means you should pack your UV islands better.
For example, all these mail assets share the same texture because they’re small objects and the style of the game doesn’t need highly detailed textures. This meant that I had a lot of small textures that I could fit onto one single, larger Texture Atlas, which is more performance friendly than eight small textures.
You can do the same with your launcher and rocket, and still unwrap your meshes to pack your islands better too 
Yeah, I fixed the UVs already. Thanks!
I have unpacked the UVs in a way that allows me to put a decal on both sides perfectly mirrored.
