I’m on an iPhone, but it probably works the same. To swipe the leaderboard away, I have to first click on an icon on the action bar that brings up a submenu, like the view/camera icon. While the submenu is displayed (thus keeping the action bar from popping up/down), I can successfully swipe away the leaderboard and nearby riders. You likely have to do the same when swiping to get the leaderboard back.