I thought they claimed a fix for this defect in one of the service packs for 2009 but I never got a chance to give it a try. I have a workaround described somewhere in here for old 2007 that still works albeit convoluted and unstable when editing.
EDIT-
If you have any rectangular structures, I think you are also going to have issues with your inverts, pipe lengths and slopes unless they have resolved those problems as well. If that is still busted, beware of any interference checks.