I installed Ardour 6.7 on my Ubuntu Studio 20.04 install and now when I am using JACK for the external time sync (for playing with Hydrogen) I can no longer start playing using the transport controls in Ardour itself, I can only start playing from Hydrogen or Carla.
Stopping time and setting the playhead both work, I just can’t start playing from within Ardour. Everything works properly, it’s just not great for the recording workflow.