Esp32 Wroom + robodyn AC dimmer

ive got an Esp32 wroom, connected up to a robodyn 16A ac dimmer.

output:

  • platform: ac_dimmer
    id: dimmer1
    gate_pin: 5
    zero_cross_pin:
    number: 4
    mode: INPUT
    inverted: yes

light:

  • platform: monochromatic
    output: dimmer1
    name: Dimmerized_Heater

i have connected it to Home Assistant, using the esphome integration.
HA has found the device and imported it ok.

but …i dont seem to be able to automate the dimmer level. (brightness) - it doesnt seem to be exposed for remote automation.
image

i can remotely turn it on/off but i cannt get the brightness to change remotely.
image

There IS a brightness control on the Lamp card - but this isnt available remotely.
image

has anyone got an AC dimmer of this type to work in HA ok ?