Guild Bar / Maze - Parties?

Hi! Recently my guild hit level 10 and so a friend and I decided to go hit up the guild bar and check out what was up with the guild maze. I had gone in earlier (and right now) on my own without a party but when I tried to enter the maze with a guild mate, both of us were stuck in the menu screen which said that the other player was still preparing. I'm not sure if this has been asked before but I tried searching and wasn't able to find anything regarding it.

TL;DR is it possible to enter the guild maze in a party or does it have to be a party?