Thanks so much for your fast answers. I unbinded my Yeelight Account from Google Assistant and reconnected it again. After that my scenes were loaded. Now commands like “Activate Good Morning” or “Activate Good Night” work fine. Anyway I still have another bug: The Scenes I manually configured are not working in Google Assistant althought they are working fine in the Yeelight App. For example I made a scene called “office” and another called “Leselicht” (=Reading Light). All those scenes are not working in the Google Assistant. Only the scenes which were already added to the Yeelight-App before can be configured and work with Google Assistant.
Anyway Thanks very much for your help!