I've been working on this map for a boom project and didn't get round to testing it in GZDoom until today. It features some large, non-solid map geometry made possible via the transfer sector height action, but GZD ignores it for these features (not for other areas of the map, mind you - there are plenty of places where 242 works just fine). This only happens with hardware rendering (it doesn't matter which renderer I choose). Weirdly, it did manage to render the objects from afar as I noclipped towards the area.
This is what it's supposed to look like, as displayed in the software renderer, but that leads me to the next problem...
In software mode, pillars at the back display the water floor texture from the rooms above as a ceiling in place of the green 'windows' seen in the foreground. Worse, the background further behind the pillars has turned into a giant HOM.
Here is a link to the map so you can test it for yourself.
I've tried it in 4.5 and the latest build and got the same result in both. This could be a settings issue rather than an actual bug but I'm not well versed in that side of things.