I can't re-enter Vault 111, it's bugged for me. I know you need the call the elevator using the red button in the cabin to be able to go back down, I've done it before. Today I wanted to go back to grab the Cryolator, but I was greated by a weird visual bug and an endless loading screen.

The entrance to the vault is surrounded by a weird looking black sphere (looks like a texture or effect not loading?), and the vault floor is not there. Using the red button in the cabin does nothing. Stepping on the vault entrance shows a black screen and the loading icon, but nothing happens. I let it go for a while, and I could still hear Dogmeat bark in the background, and I heard a nuclear storm brewing in the distance. Once you start the loading process, you're stuck there and can't do anything but reload your game.

I have not tried reloading an earlier save, as I don't have one. I keep multiple saves at all times, mainly because if I get stuck somewhere I'll load an earlier save. I have no idea though when this area became bugged, or for which reason.

I took a screenshot, here's the link:

imgur.com/thh23ql