Hi Dan,
Could you please have a look at: [SOLVED] Alexa can´t reach devices exposed and added to the Alexa app
I‘m out of ideas and need a hint where to search next.
I was able to solve the issue with the help of Gabriele.
The items are only allowed to be defined as Number and not as Number:Temperature.
Is this a bug in the skill, exposing or the core?
Thanks!