No sound through HDMI?!

[spinal]

Hi everyone. I'm new to tinkerboard so this might not be a difficult issue to solve.
I have tried a couple of OS's on my tinker so far, but I have settled on the idea of android. The problem is, I have no sound through HDMI.
I originally tested 20170511-tinker-board-android-marshmallow-userdebug-v13.11.0.4.img which worked perfectly for a few hours. It had sound, the couple of apps I tried worked etc. However after shutting down, it never booted up again, I just got a black screen, sometimes with 4 penguins at the top, but nothing else.
Next I tried 20190515-tinker-board-android-nougat-userdebug-v14.3.2.82.img and 20190103-tinker-board-android-nougat-userdebug-v14.2.2.73.img. Both booted fine, even after restarts, however neither have audio at all. I tried googling a solution but after double checking my settings and even manually fiddling with the audio setting through adb, still no audio.

I have just this second downloaded 20191227-tinker-board-android-nougat-userdebug-v14.4.0.5.img which I will try today.

Does anyone know the solution to this issue? I'm using the 'normal' tinker board, (not the S) and have also tested on 2 different TV's.

Thanks in advance.

[edit] Audio works through the headphone jack no matter what my output settings are.