Can't redo Mouthpiece on normal or Mayhem mode?

I can’t go back and kill Mouthpiece after completing the campaign. When I get into the building that he is in there is a metal gate up like I haven’t completed that part. Please help…

I had this problem at first but then I figured out if you have that side mission where the twins are looking for another mouthpiece the gate will remain closed. Complete the side quest to have it remain open.


Thank You! :sunglasses: