I don’t know if anyone else is having this issue. I have killed Psycoreaver like 5 times and each time after killing him there seems to be a barrier around the portal. The only time I made it into the vault was the first time, completing the story. That time I couldn’t reach Sane Krieg to talk to him. I had to teleport to a different area and then back. It seems that some sort of glitch with Psycoreaver’s body is preventing me from getting close. In the subsequent wins when I beat him and then teleport to another map and back the portal is gone.
I kept trying to find an answer to this or see if someone else had this issue. I do think this issue was caused by the giant head mod. I went into my mayhem mode modifier and made sure the giant head modifier wasn’t actvie. Then I fought Psycoreaver again and was able to enter the vault