Changing playlists using Google Assistant

[tech_fan]

How can I accomplish the following:

1. Tell Google to play a specific playlist on Google Play Music. Playlist starts to play.
2. While the music is playing you activate Google Assistant again and tell it to play another playlist. It acknowledges receipt of the request but continues to play the original playlist.

This happens both on Google Play Music and Spotify. I have tried telling it to pause music or stop playing but then it just googles those commands.