RBXM mesh files problem (HELP ME)

I got this problem with my RBXM files where my meshes won’t load.

This picture is supposed to have a body of full armour and a helmet.

Can anyone help me on how to fix it please? I really need these to work.

I try and make it an OBJ and import it, it still happen’s.

So I try and import it as an object into “3d builder” and it still doesn’t work.

Are your normals inverted? You can invert the normals by pressing CTRL+SHIFT+N with the mesh selected in Blender.
Please make sure to search around the forums, Google, etc. as most of these problems have an extremely well known and well documented solution.