Tuya ERS-10TZBVK-AA and setting action_step_size

Configuration Zigbee
1

So I have one of these controls:
https://www.zigbee2mqtt.io/devices/ERS-10TZBVK-AA.html

It is running in event mode.

I’ve paired it via Z2M and it works (doesn’t see double or hold properties … but I can work on that later).

I’m trying to use it to control the volume on my amplifier … but the default increments are too small.

I’ve tried playing around with the yaml and action_step_size. However the action_step_size value always stays at zero.

Here’s my YAML …

  "0x187a3efffed6529f":
    friendly_name: RZt Black Knob
    device_options:
      action_step_size: 40

Just wondering if anyone has any ideas to help me adjust the action_step_size?

All the best

Jason