In the Track View, go to Options > Click Behavior and uncheck "Left Click Locks Scroll."
The idea is that, if you click to edit data with that enabled, we stop scrolling so that you can continue to make adjustments in the area you're working in. When you want to start scrolling again, you can right-click the top half of the time ruler. It's supposed to re-enable scrolling after you stop/restart playback... But that doesn't appear to be working correctly.