See through part when not meant to

Hi basically i made a bevelled base see https://postimg.cc/Wdg6LkQD and it looks good, but when i import it into roblox studio, it looks weird, see https://postimg.cc/bsKHBTFc
What did i do wrong? Can somebody tell me?

Might be inverted normals. Some programs/render engine renders inverted normals as transparent.
Try checking if some of your faces have inverted normals.


Red is inverted, blue is correct.

If you do have inverted normals you can recalculate it by selecting the faces in edit mode and press shift-n, if it didn’t change you can tick the “inside” button on the window that pops up.

Mine is blue

Maybe try shade auto smooth.
image

Were is that?

Object data properties.
image

Ok! I will write it down so i remember, i am trying to make a leaderboard and want to know how to make the sign like the one on the picture can you tell me how i can make it look like the one on the picture i attached?

I fixed it! Ty!