Oh no! What is the status of System Preferences > Keyboard > Shortcuts > "Use keyboard navigation to move focus between controls"? If that is off (the default), this is expected to work. If it's on, focus will first go to the row-collapse button.
Hi Ben, if you *un-check* "Use keyboard navigation to move focus between controls" (unchecked is the default), then this should work as you're expecting.
With that checked, full-keyboard-access to all controls is enabled. We have a bug open to figure out a solution.