Use the latest RFXflash version 12.0.0.0 or higher !!!!

Important information about RFX433 firmware:

RFX433 firmware will only operate in the RFX433XL-USB/WIFI/LAN, RFXtrxWifi-RFX433 or RFXtrxUSB-RFX433.
!!!!!!  USE RFXflash TO FLASH THE RFX433  !!!!!!
We have received several problem calls of a frozen RFX433 when flashed in Domoticz.