I've managed to install the script and discovery without issue. The problem lies when I issue out MQTT commands.

I can verify that the script connects to MQTT Broker and subcribe to the necessary topics. I've been able to listen and receive messages. However, when I issue activity commands there is no response. Only when I issue an activity command as "off" would EVERYTHING turn off. (as said in the documentation)

So clearly there seems to be an issue with responding to MQTT commands.