Xbox
I have the safehouse in bunker. Respawn is inbetween last two blast doors. They are locked again. I have come in like i did first time, tried to turn power on then off. To no avail.
I have every main and side mission done except for A wrench in the works.
Yeah, same thing happened to me as I didn’t noticed at first because I assumed it’s unlocked. I fast travel to Uttern Bunker, both blast doors is locked again.
This is on Xbox, too.
Same issue with Marden Command Bunker.
Same here, jumped to Marden for a little “ammo run” and the big doors are locked now.
Haven’t been there since the update so it’s related somehow to it. Before everything was fine, no issues with the bunkers, except the Tunnel rat achievement not unlocking.
All missions and warboards done, playing solo on PC
I have also encountered this Bunker bug with doors locked recently on a few bunkers not just the Nutter bunker >> Work around join a multiplayer game and fast travel then leave and try again 
good luck it’s not ideal but it’s all we got for now , cheers