Mesh Colliders are not functioning as expected under the 2018 build, I have also reuploaded the world using the new version of unity. This is causing me to fall through the floor on spawn as well as any items around the world are falling through, I am being stopped by the terrain colliders on the ground. The surfaces are set to Default layer, also so you are aware.
World (WinterZ Vaporwave Home)
Here is the link to the 2018 build