After a little more investigation, resuming actually does work. Ubuntu just isn't properly enabling the HDMI display when it comes back. If I press the keyboard button to swap between internal/external display a few times, the HDMI display comes back on.
After a little more investigation, resuming actually does work. Ubuntu just isn't properly enabling the HDMI display when it comes back. If I press the keyboard button to swap between internal/external display a few times, the HDMI display comes back on.