hi,
At the time of writing, in all game modes (except for custom game) when we try and queue up in a party it says
There was a temporary problem with your request. Please try again later
a brief moment after the last person group leader [updated after original post following more testing] presses the “Ready” button. About a second later the last person to press ready looses their “Ready” status.
Queuing into game modes solo appears to work.
Update on this:
The problem is still happening - however!
Although everything seems normal in the game, including your own portrait showing, if you go into Collections → Portraits not all of the portraits are shown, there are instead a load of empty squares.
Exiting and relaunching the game until all the portraits appear in the shop then allows you to queue up in a group.