Bug: Instance geometry extending on compile

[Equalizer5118]

Describe the bug

I am using a modified version of the departure elevator base from the community instances, and I have a hallway that is connected directly to the entrance. In Hammer, everything looks fine, but in-game, the floor geometry at the start of the entrance of the elevator extends into the hallway and completely the floor. This is purely visual; portals can be placed where able on the normal floor.

Hammer:

Game:

Issue Map

https://www.mediafire.com/file/44bfpbw9wwudkbm/floorbug.7z/file Included is the vmf and the instance used for the elevator base

To Reproduce

1. Open above map in hammer
2. Compile map
3. Observe bug

Operating System

Tested on Windows 11