You don't have to switch anything, those are just preview settings for the cloud room. The clouds will show up if they are not hidden from view. The only time they will not show up is if they are in the extreme distance when the atmosphere is set to 20 or 25 miles, but I doubt that is the case here. You should be able to see the bounding box of the cloud in the assemble room. Try going to 4 views to better see the actual postion in the space. Sometimes using only the director's view can be misleading.