Alexa Device not found

Hi All. Thanks for the add. I am totally new on node-red so please excuse any dumb questions

I have Node-Red under HA on an rpi 4 which is wired to my Unifi UDM. I am trying to use the 'Alexa Home' node but it cant find my one and only test device. Node-Red seems to be connected to my account ok. If I go onto my Alexa app, I can see the device. Its a simple on-off device which uses a Shelly 1 relay through MQTT. Trying to switch the device through the Alexa app gives me a warning "waiting for Node Red". However, back in the 'Alexa Home' node in Node Red I don't see any devices. I have refreshed and told Alexa to "discover devices". Any tips on what to look for? Thanks

I should also add that the device shows up on
https://alexa-node-red.bm.hardill.me.uk/devices
Thanks