Alexa Integration of electronic Radiator Valve


I have a fully functional smartthings device that works well until I try to add the device to Alexa.

I receive the following :

error : thermostat mode state is invalid
debug : handlePostV3

I ma hunting down the handlePostV3 documentation but suspect the thermostat mode issue is down to the mode I have set, the response format or maybe a simple lack of response!

I can’t find any info.

Support have been hopeless in even identifying where I can find information.

Any pointers gratefully accepted.