I'm having a visual issue with one of my Doom maps

So, I was working on my 3rd map for an upcoming megawad. And I noticed a visual issue with specific areas, like these stairs in one room and the floor after the other room.

However, in 3D mode, it looks completely fine. Any fixes?

The 3d view isn't an accurate representation of what the game looks like. 

Can you share the map file so we can have a look what's going on with the sector? 

2 hours ago, Sneezy McGlassFace said:

The 3d view isn't an accurate representation of what the game looks like. 

Can you share the map file so we can have a look what's going on with the sector? 

Sure, here's a copy of the two rooms from MAP03. It replaces the first map, so no need to use cheats to skip to the third map.

MAP03.zip

4 hours ago, Z0RGUSSY said:

Sure, here's a copy of the two rooms from MAP03. It replaces the first map, so no need to use cheats to skip to the third map.

MAP03.zip

Very interesting, that seems a node builder issue. Because I can see the error in both nugget-doom and crispy-doom but when I open it in my editor and hit save, it gets fixed automagically. Maybe choose different BSP in your editor's preferences.

And as for the door border, I get report of missing backside upper texture (line #109) which may be causing some issues too. But I think the main problem is the borked nodes.