Blue Floor Problem
Ok. Dled the lot. Found a fix. Just have to drag a wall to make the tile match the rest in the room. See my pic below for which arrow you need to grab. It's the one circled.
This pic is the after shot to show the color changed to match.
I thought you might be missing ceilings and that was causing the problem as it's a lighting issue. But, nope, even though the ceilings are missing in a lot of places throughout the build, that wasn't it. I'm not sure why that section of floor tile is not matching though. Probably has something to do with the combination of the platform and round wall sections you've used but I really don't know for sure.
Anyway, just drag that wall section to the door and it should fix it in your game as it did in mine.
Hope this helps.
