It can sometimes happen. Make sure you used the correct static pieces that are normally used, not some scripted variants and whatnot. If that doesn't work try removing and then re-adding the missing pieces, that worked for me too. Sometimes it just didn't make some things appear for no apparent reason, when I deleted them and placed the exact same object on the same spot it worked. Not sure why this happened so I can't offer you a better insight over the problem.
Of course, I provided this answer under assumption that you're having disappearing objects in exterior, if you're having trouble with interior that's a whole different story including room bounds and whatnot.