I'm on a Note 3 and what's happening is that I can get Google Voice to launch the Google Play Music app by voice command from Google Voice but it won't actually play anything.
If I say "Play Cream" it will launch the Google Play Music app and bring up a thumbnail of the album, but doesn't play it. Apparently there is no voice control for the Google Music App so it's pretty useless for things like driving.
I set the default music player back to the built in Samsung "Music" app, which does have voice commands and it works reasonably well to use Google Voice to interpret the commands (S Voice doesn't work very well) and the Samsung Music app to play the music. To set this up, use Google Voice to play something, e.g. Play Cream. That will bring up the Google Voice music screen and there's a little pull down at the lower left where you can select the app to play. Then hit the Music label and once you've played something, it remembers what you used to play it with.
I have the exact same issue..and it's so annoying.
"Listen to 'August Burns Red',.....
>playing 'August Burns Red' (with artist thumbnail
>google play music opens, artist thumbnail appears
and like you, i have to tap the artist then find the song/album i want. so really, Google voice commands (regarding playing music) are just frustrating and not really hands-free as it should be.
UPDATE: Just got a response back from Google support: "The reason it has you tap on the song/album/artist is because the Voice command option is a feature that Samsung provides. It is a search feature and that is why it requires you to pick what you want to play. What I have gone ahead and done is submitted a feature request. "
I can confirm that the same issue occurs on my Samsung Galaxy Nexus, Samsung Note 3--
but my brother's LG Nexus 5 begins playing the artist instantly.
Verizon Galaxy Note 3 (4.3)