Opentherm gateway thermostat setpoint rounded to whole number

Hi, I’m having an issue with the opentherm gateway integration. Hardware and integration are working fine but when I set the the temperature of the thermostat via automation or just the thermostat card it rounds the half values to round.
For instance if I set the temp to 18.5 it sets the thermostat to 18.
The thermostat support half degrees and the configuration of the integration is set to 0,5 as step.

What could be going wrong?