Sorry to hear you're having trouble with this level, we actually identified what we believed to be the root cause of this about six months ago after finally receiving a save file with the issue in a replicable state so I'm surprised to hear that you're still encountering this issue. We've not actually received any reports in quite some time.
Can I ask what occurred in the run up to this issue happening, can I also ask whether you've loaded an old save or started fresh from the campaign map? If it's a save it's possible the bug is still present in your save and you'd need to start afresh I'm afraid (if you don't want to do that we can cheat you past the level if you wish) otherwise we'd love to get our hands on your output log and save file from this session!
Please have a read of How to: Submit a Bug Ticket and chuck us as much information as you can and we'll look into it in the new year!
Sorry once again and hope we can solve this issue,
Customer support service by UserEcho