Xbox multiplayer issues

I just unlocked the final gate in the goat tower with my friend. When we go to enter the gate it kicks me out of his game. Am I not able to play whatever is in the gate in someone else’s save? It’s really frustrating because we spent a good bit of time trying to figure out how to unlock the gate and was so excited to see what was in there.

I missed the cutscene but was able to join after my friend watched it, we were able to beat the boss after multiple attempts. Each time we lost all of our health I was kicked and had to join mid fight again. After we got to the part where the whole game ‘crashes’ and you get blue screened, I was kicked and couldn’t watch the credits or get the Farmer goat skin.