Spotify is the default music app on my Google Nest Hub. My Google Nest Hub also has VIZIO soundbar as the default speaker (all of these are configured in my Google Home App on my iPhone with the latest iOS). When I give voice commend to play music, Google Nest Hub will open Spotify and play the song and the sound will be played through my VIZIO speaker. However, every other song is silent. If I change Google Nest Hub's default speaker to Google Nest Hub's speaker, this issue goes away. I tried the crossfade setting and it doesn't solve the problem.