HDMI audio only works on hot plug (not cold boot)

I’m having an odd issue getting HDMI audio to work properly. I’m running Debian on a Zero connected via HDMI to an Elecrow 5" display with speakers (https://www.elecrow.com/rc050s-hdmi-5-i … ntrol.html).

When I boot the Radxa Zero with the display connected and powered I’m unable to get audio to play over HDMI. However, if I boot the Radxa Zero first and connect the display after the boot sequence, I’m able to get audio to playback on the display. In both cases, alsamixer shows the same settings, and pavucontrol shows a moving sound bar, e.g. the OS appears to be playing back audio even though in the ‘cold boot’ case I don’t hear anything.

I’ve tried connecting different displays via HDMI and don’t see the same issue, so have a feeling it has something to do with how this particular display is initially being detected during the boot sequence, but am at a loss as to how to debug further.

Kernel I am running:

uname -a
Linux xxxxxx 5.10.69-12-amlogic-g98700611d064 #amlogic SMP PREEMPT Tue Jun 14 12:47:53 UTC 2022 aarch64 GNU/Linux

Thanks in advance for any help.