Please can you show us what messages are returned by the MQTT node (using the debug node - copy and paste), we will have a better idea of the message structure and be able to help more rather than just having to make a guess. I, for one, don't have access to a Fibaro Motion Sensor.
I recommend watching this playlist: Node-RED Essentials. The videos are done by the developers of node-red. They're nice & short and to the point. You will understand a whole lot more in about 1 hour. A small investment for a lot of gain.
Thanks for the prompt response.
I will definitely spend some time looking at the videos.
My query has been answered below but again thanks for taking the time to respond.
Doh!!! I feel such an idiot. I was using a change node but tried putting in what I thought was the full structure.
i.e. setting msg.payload.object.value to msg.payload as that is what I could see in the debug logs.