Why do I get an error of no speakers connected when sending a message to all in Google Home app?

When trying to send a message to all in Google Home app I get this message saying that no speakers are connected: > “Entschuldige, anscheinend sind derzeit keine Lautsprecher mit deinem Konto verbunden. Deshalb kann ich keine Nachrichten übertragen.” #### English translation of message provided by Apple translate. > “Sorry, there seems to be no speakers connected to your account at this time. That's why I can't transfer messages.” However my speakers (Samsung HW-S711GD Ultra Slim Soundbar, 2 Chromecast Audio, 1 Chromecast with Google TV HD) are connected and streaming to them with Google Assistant works (for example using: Ok Google, play radio XY on chromecast). I am assuming that by sending a message to all the Google Assistant will play this message on these speakers. Is this assumptions correct? What could make the assistant think my speakers are not connected?