I am using version 3.2
I created an empty project based on the Scrum template.
In it, I created a story which is not assigned to any sprint and the (Current Sprint) variable is not set yet... So the query shown in the first image of the attached screenshot ("Sprint backlog" tab) should work. But the board is always empty and the message at the top reads "There are no cards that match the current filter - Reset filter"
I've created a custom tab (second screenshot in image attached, "Story board" tab) with the exact same filters and the story does appear there... what's the catch?