Waiting for soundcard to populate failure (JustBoom Digi Hat)

With my aging SB3 going into "reboot after starting playing" mode (since fixed with a capacitor change), I looked for an alternative and found piCorePlayer. I quickly put together a system with a 7" display, an RPi 3B, a JustBoom Digi Hat and a Touch 2 case. It works brilliantly, with a couple of caveats.

Sometimes (1 in 2 times?) the boot sequence has a failure with the line:

Waiting for soundcard sndrpi.justboomd to populate......... Failed

It takes maybe 10 seconds or so for the failure to be flagged after starting to "populate". Unsurprisingly there's no sound when this happens. When the failure doesn't occur the "populate" step happens in well under a second.

Possibly related to this, as I was rebooting the system overnight each day, when I try to play something for the first time most days, the player appears connected to the server (on a different system) but refuses to play anything. The progress bar on the Now Playing screen appears but no time elapsed/time remaining are displayed and the screen just twitches when pressing the Play button on the remote. I have to reboot (usually twice because of the "populate" problem) to get sound back. I've switched off the overnight reboots to see if that makes a difference.

I'm running: piCorePlayer v7.0.1 | www v00015 | linux 5.4.83-pcpCore-v7 | piCore v12.0pCP | Squeezelite v1.9.8-1344-pCP

Can anyone tell me or suggest:

1) What's causing the failure of the JustBoom Digi Hat initialisation?
2) The strange lack of audio (assuming it's not due to the reboot)
3) How do I know when there's an update for pCP/SqueezeLite? At present, I just click the update buttons in the web interface every two-four weeks.

Cheers, Steve