Not sure what is going on but when I click my middle mouse to rotate my assembly, the assembly zoom out all the way and even if I use "Zoom to Fit" my screen is still blank. I can only get my assembly back on the screen if I "Undo". If I exit SW all is well but after a few commands it happens all over again. I know I'm doing something wrong but I can't put my hand on what I'm doing. Have anyone else seen this? I tried to record it but the assembly goes so fast its hard to show what's happening.
My best guess it that one or more of the parts are located way off from the main assembly. You might try "zoom to selection" on each item to see if this is the case. Another possibility is that the assembly itself is not on or near the origin.