I am on a Windows PC many hours a day. I am used to using the Windows Spotify app which allows me to cast to any of my Amazon Echo devices or Speaker Groups. I just joined Amazon Music Unlimited and installed the Windows app and discovered the app does not seem to support casting... it only plays on my PC speakers. Surely Spotify has not “out Echoed” Amazon? BTW, I have no problem finding/using the cast icon on my Amazon Music for Android app.