No sound on Ubuntu 18.04 LTS RPi3

I am trying to set up OP25 on a Raspberry Pi 3 B running a Ubuntu 18.04 LTS (lubuntu-core desktop). The software installs fine, however I cannot get any sound out of the Pi, via HDMI or from the analog output. Here’s what I have tried.

1. aplay -l returns aplay: device_list:270: no soundcards found...

2. Tried removing pulseaudio and alsa, reinstalling, does nothing.

3. Tried reconfiguring hdmi/3.5mm jack (sudo amixer cset numid=3 1), no result.

4. Tried using inxi, no audio devices found.

5. modprobe snd_bcm2835 returns [1948.563781] bcm2835_audio bcm2835_audio: Failed to get DT property 'brcm,pwm-channels'

6. Tried adding dtparam=audio=on to config.txt, no result.

The Pi itself is not defective, when I installed Ubuntu MATE the sound worked fine. My preference is to have the server running lubuntu-core, as I only need minimal features.

Any advice will be much appreciated.