When the camera is perfectly aligned with axises, some triangles are not rendered on the MTT S80:

How to reproduce:
setviewpos -2256 2296 200 -180 0 on plat23
The triangle is entirely missing, what we see being drawn there is the remain of the previous frame, i.e. we see the void.
It is almost invisible when playing because when moving the void is filled with the surrounding texture that was drawn in the previous frame before moving, and it would only do that at the exact moment the camera is perfectly aligned on axises
Here we see the spawning halo effect.
If we do setviewpos -2256 2296 200 -180 0 as a spectator in plat23, we see the remnant of the default spectator scene in the void instead:

If we do setviewpos -2256 2296 200 -181 0 the bug disappears:

If we do setviewpos -2256 2296 200 -180 1 the bug disappears as well:

So the bug doesn't prevent to play.