Time: Slightly after 8:15PM UTC +8
Frequency: First time happened
World name: Tonberry
Character name: Flipp Fuzz
NPC name: N/A
Monster name: N/A
Class/Level: 60 SCH
Party or solo: Party Leader in a 3 Party Alliance (Alliance B)
In-game time: N/A
Area and coordinates: Lavender Beds Ward 6, Housing Workshop

Same as Endracion.
I was the last party leader to ready the airship for the mission. (Selected airship 4)

This is likely to be the known issue under investigation, but will just post in case more information helps.

http://eu.finalfantasyxiv.com/lodest...a1c43b9676b389
[Issues Being Investigated]

・In “The Diadem” party leaders may not be able to enter properly when entering as an alliance.
* Until this issue is resolved, we ask that you consider not entering as an alliance.