Hi Zornhou. Correct behaviour should be that both left/right and up/down arrow keys should work regardless of the orientation of the timeline. So when in vertical mode both the left arrow key and the up arrow key should move one card up, and right/down should move one card down.
Are you saying that while in vertical timeline orientation the up and down arrow keys are not working for you at all? Do all keys work in horizontal timeline orientation or is there a similar problem there?