I installed the Tempest/Weatherflow Alexa skill some time ago and it worked well.
Now when I say “Alexa ask weatherflow what’s the weather”, Alexa just gives me the normal (not Weatherflow) information.
The only way I can get to the Weatherflow information is to say “Alexa ask Weatherflow” and then response to the prompt from Weatherflow and then I can ask “What’s the weather”
For what it’s worth, I have the integration installed as well (from a while back) and just tried “Alexa ask weatherflow what’s the weather”. I got back exactly what I expected. Maybe there was an issue with the Alexa backend, I’d be curious to see if it’s working for you now.