Sonoff TRVZB and Advanced Heating Control

Hi, here are the components of my system:

HA on Raspberry Pi
Sonoff Zigbee 3.0 dongle - latest version
Sonoff TRVZB
Sonoff SNZB 2d

So far, I’ve managed to install MQTT and Zigbee Home Automation, thermostat and temperature sensor are visible. But I can’t get “Advanced Heating Control” to activate the valve. I have an automation running, and in the event log, I see the following entries within a 3-second interval:

SONOFF TRVZB HVAC action -> status changes to "idle"
18:00:47
SONOFF TRVZB HVAC action -> status changes to "heating"
18:00:43

Btw, is it possible to achieve full-range (step-by-step) or PID control of the valve with the Sonoff thermostat, or is it limited to on/off control only?