Help my mesh is invisible

[UnTagifier (hot_dog)]

Hello, I am importing a volcano mesh and it is almost invisible in RobloxStudio. Here is an image of it

somebody please help.

[Marrsons (nothing_special)]

You just have to flip your faces, here is tutorial for it, its pretty easy to fix

How to Flip Face Orientation | Flip Normals | Blender 2.9 Tutorial

[grimmerschool2 (ToasterGrim)]

Your normals are messed up.
You can fix this by pressing A in edit mode, which will select all faces. Then hit Alt + N, then Recalculate Outside.
If any face normals are still messed up, do the same, but Recalculate Inside.

[UnTagifier (hot_dog)]

I fixed it by making it 2 sided. Sorry.

[grimmerschool2 (ToasterGrim)]

Alright. Good luck with your game development.