Really think this is part of the Preview Bug? While this was foundry-releated and BOFFs warping disappearing, I encountered something similar with the Romulan Werehouse mission. BOFFS disappeared and Warped.
So hopefully they will soon find the error. Really would suck if players got 1 stared because of it.
No matter what I do in trying to fix things, nothing is working. Changing the Y values isn't helping, and changing the Zero Alitude doesn't help, weither if it's Zero, Room Floor, or Legacy Room Floor.
But I noticed that in normal pre-made zones, they aren't warping or falling through the ground. So apparently the Foundry is not accepting the customized Foundations as valid floors.