This is probably a design flaw not a bug, but I had a group of colonists return from asteroid mining, and half of them died of suffocation a few steps off the rocket on the way to the dome. Their O2 levels should have been reset to full once they were in the rocket, I would think. Its always a race to build their habitat and power and water and O2 buildings on the asteroid before they start suffocating, and then the same problem taking them down when finished. IMHO they should stay aboard the rocket until their habitat is built and powered and supplied with air and water. Then during packing up they should get on the rocket, not stand around watching drones and wasting their air.