Mesh partially disappears when going inside of it

Ok so I started working on a game in Unreal Engine 4.27 and since this is a soccer video game, I had to make goals. The goal’s system is easy but this is the thing I’m having the problem with:

I made the goal in Blender and imported it into UE4 and when I first imported it, it gave 3 warnings saying this:

"No smoothing group information was found in this FBX scene. Please make sure to enable the ‘Export Smoothing Groups’ option in the FBX Exporter plug-in before exporting the file. Even for tools that don’t support smoothing groups, the FBX Exporter will generate appropriate smoothing data at export-time so that correct vertex normals can be inferred while importing.

goal_Cube has degenerate tangent bases which will result in incorrect shading. MikkTSpace relies on tangent bases and may result in mesh corruption, consider disabling this option.

goal_Cube has some nearly zero bi-normals which can create some issues. (Tolerance of 1E-4) "

And I got 1 error (or whatever that crossed off symbol means) saying this:

"Mesh name: [goal_Plane] part name: [Plane] could not be created because all of its polygons are degenerate. "

I’m not sure if this is relevant to the issue but I just cleared those messages out and tried to put the mesh into the scene. It got put into the scene but
whenever I turned in one direction, one of the faces of the mesh would disappear. This is probably because the goal is made by deleting 2 faces from a cube and I’m not sure how to make unreal stop making the faces go in and out.

I can’t put a video of what it looks like because I’m apparently a new user but this is really annoying.

Also, the goal has a glossy and glassy material and when I import it into ue4, the glass and the gloss from the material are both gone.


never mind another topic was already on this and solved my problem