Ceiling Grid disappears

[Griff]

I'm really confused. I have a 2x4 ceiling grid with several lights, supply and return fixtures installed. If I try and add another 2x4 troffer light my whole grid disappears. I can add more mechanical fixtures without a problem. I can even install a 2x4 linear box light fixture without the ceiling grid disappearing, but when I try to install another 2x4 troffer I lose the grid. Any suggestions?

[Griff]

I don't understand what was causing the problem, but I decided to just delete the ceiling and redo it. It works fine now.

[sbrown]

Its just one of those revit things, just move on as quickley as possible and don't look back.