Mission continued to crash repeatedly for me. I wasn't always in combat when it happened. Using my rally point and keeping BOFFs in the tunnel part seemed to help and slowly I was able to progress just enough to complete it.
Just encountered this bug today. The mission objective states to "Explore the surroundings" and never progresses despite my repeated thorough exploration of the entire level. I'm appalled to see that this bug has been around since 2009. That's going on six years now! How could the devs let such a game breaking bug exist…