Sure, I have just been caught up with making a Unity VR demo for an upcoming BIM day
(not with this model)
This model is just a wip of our old house, the model has gone from V4->V5->V6, I would not be surprised if you find some bad objects in there either, this is for my own use so "good enough" is "good enough" ), but the issue doesn't appear all the time, so I saved it in a state that consistently shows the bug on my Quadro 4000 machine, I'll test it on the GeForce 970 machine in an hour.
Open the file and click on wall 1 and then on wall 2. That triggers the issue here at least. Sometimes the floor disappears, other times wall 1 disappears, and then reappears. It almost seems to be related to some background calculations of some sort, but I don't know.
Here's the file:
HolosHouse V6 hide shade bug.zip (706.3 KB)
Also, OT, but since it is related to the file:
Can you add a "remove missing image file" option to this outdated pop-up?
And add a propper icon to each file instead of the grayed out "A swap B" icon, that appears inactive, until one clicks on the missing file name.