I'm having a similar issue. I get into the elevator, but the 5th and 6th floor buttons both go to the 6th floor, and I can't seem to get to the 5th to complete Jezebel's portion of the questline, and as I'm Tremere, that screws me out of my Haven and more plot.
Going to try the vents, see if that helps, but doesn't seem likely. Anyone else have this issue?