Hi heme3ic -
Since your map is opening without error for me, Can you run the following test on the BSPs that are invisible? In the Editor, fly your perspective to inside one of the columns and see if you can see it. I am looking specifically to see if somehow the vertex normals have been reversed.
As a means of trying to get you back to work, create a new blank project with NO starter content (if your original project is a code based project duplicate that in the new project) then move the contents of your Content Folder (and Source if code-based) to the new project. Doing this has been known to rectify the vanishing BSP issue in the past.
Also have you done any Flip Face dynamics on your BSPs?
Let me know of the Test,
Thank You
Eric Ketchum