Hello fellow Dev Forum members! Today I have another issue that needs to be resolved. Recently I had the brilliant idea of making a simulator game so I could fund my group and give it a kick start. I played around with Blender 2.8 and made some low poly terrain to build the map with. It looked good so I exported it into Roblox Studio and it didn’t turn out too well. The terrain looked hollow when it was in Roblox and it probably wouldn’t look to nice for use in a game.
From what it looks like you have some normals flipped. Normals are the “sides” of each face on your mesh that actually get rendered and can be seen by the player, so since your normals are flipped (meaning you can see the object from the inside, but not from outside) it appears like that.