New bug for me, although its only happened once in nearly 60 missions it was a bit annoying.
Swapped to my Heavy Bolter just before the mission and when it loaded up the Bolter was gone!
There was nothing in the 4 ability slots, nothing in my hands and my character just "glided" around instead of walking.
The other weapon set worked fine but no Heavy Bolter, and the worst thing is IT DIDN'T COME BACK!!
After the mission the slot was empty, and that was my favourite Heavy Bolter too! :)