HDMI shutdown

I have a Pioneer FreedomBox installed from a recent stable build.

When I boot my fbx (by plugging in the power supply) the HDMI display shows the booting process for a few seconds and then goes to a blank screen. If I then unplug my HDMI cable and plug it back in the login screen is displayed for a few seconds and then the HDMI signal is dropped and my monitor powered down.

I can reproduce this issue every time I boot or plug/unplug my HDMI cable. If it's useful I could create a video to show the problem. Ideally the HDMI display would work reliably and allow me to login via tty1.