I cannot join the event. I have just 2 options: Visit Steam and Sync games.
I have added Dota 2 to my library already, but Sync games button doesnt help.
(but syncing worked for Steam quests today)
EDIT: issue fixed (thanks to @Daytraders)
(but syncing worked for Steam quests today)
EDIT: issue fixed (thanks to @Daytraders)