You can re-do isolation vaults in the same run, but it's super buggy and you don't get any drops

[motorfirebox]

Title. I was messing around soloing vaults, and I decided to hit up Gross Mom for the T1 vault after I'd already completed it. She gave me the mission, Loid/Otak spazzed out a little before telling me the door was open (didn't have to collect more wyrm guts), and I went in. The first two phases activated, but only the objective mobs spawned—just the infectious infested for the survival phase, and just the necramech once I got inside. The necramech didn't drop anything at all once killed. I couldn't summon Loid/Otak after killing the necramech, but it didn't matter, the vault was still open from my last run and hadn't spawned any new containers anyway.

I did get the mission rewards, once I left and headed back to the Necralisk, so I guess there's some minor exploit farming you could do there if you wanted.

Anyway, seems to me like it should be one or the other: either you shouldn't be able to re-activate the bounty for completed iso vaults before you leave the Drift, or re-activating bounties for completed vaults should actually reset the vault for that bounty.