I am modeling a three story (basement + 2 floors) 35,000 sf institutional cafeteria with complex floor plans. There are three atrium spaces in the above ground portion. So far I have created spaces for each floor using imported DWG files. The atriums are divided horizontally by floor at this point. I used a workflow based on this link: (https://unmethours.com/question/3951/...). It seemed to work very well to stack the three floors in the proper position. The geometry showed up as white spaces. I saved and closed the osm file, restarted Sketchup and opened the osm, there was no geometry at all. It occurred to me that perhaps some of the space names were identical, so I repeated the process after assigning unique space names and had the same results.

I am using Sketchup Pro 2016 and OpenStudio on a Windows 64-bit machine.

Any ideas on the best workflow? Thanks!