Illager Intelligence side quest - final door on the roof not working

I’ve encountered a progression stopping glitch that will not allow me to complete the Illager Intelligence Side Quest.

• Couch co-op with 2 players

• on the roof of the castle where there are 3 door portals

• at the left-most door (3rd door to check), when we go in, it spawns only P1 back outside in the same location

• p2 is missing at this point entirely from the screen

• If P1 goes back into the middle door, P2 reappears there

We cannot complete the mission without entering the 3rd door - and we cannot get to the side quest at the top left of the map since it’s dependent on completing illager intelligence before being accessible.