Units and Levels Disappearing when Z Values are Changed

[GAVINMAURER]

Hello!

So I have been working on an indoors model of our campus for over a year now and I have recently just tried making a 3D scene out of it. I discovered that a lot of the units and levels from buildings have incorrect z values or sometimes just have a z value of 0. Now for a lot of them I have been able to edit them no problem but in a couple cases when I change the z value on a unit or a level the entire thing will just disappear. All I can do to fix it is undo the edit. So then I am stuck with a weird floor crossing polygon. I wouldn't think that changing the z value would mess with the Level ID or anything like that hence my confusion!

Has anyone else had this issue or know a solution?

Here are some supporting images!

Thanks!

Gavin

[MollyE]

Is the elevation in the layer properties set to "relative to ground"? I'm not entirely sure but since you're dealing with basement layers and negative z values, that may play a part. 
That would affect the whole units layer though, so if you have other polys in the same layer that are showing up correctly, it might be something else.