I know this is a bit of a bump, but this is where I can post something relevant lol,
I was playing the demo, mission one last night with Geoff and Michael Rouke. Not long before we had enough supplies to be able to take off, the Cohab ended up running out of oxygen so we ended up dashing around trying to get more O2.
It was quite funny, but we never managed to restore all of the O2. Perhaps adding in a backup unit would be good if it hasn't been done as you would expect there to be more than a single O2 canister.