Spotify Connect not playing local files on Yamaha MusicCast!

[Granzita]

1/ (On Macbook Pro + Mac OS Sierra)
Spotifiy does not play the local titles when Airplay connecting to Yamaha WXAD-10 receiver through MusicCast App: The titles appear like unaivailable (dark grey).
But Spotify is OK to play them when bluetooth connects to Yamaha MusicCast: the titles appear then available in white!
I would rather not use Bluetooth because of the huge lost of quality and power of sound, neither because of the unstability of signal through a big room.
2/ (On IOS 10.0.2)
Secondly the Spotifiy App does not show those local titles on the playlis on Iphone (however they are in the Itunes downloaded files) and visible in the same playlist on computer…
Any help??

[Rejzor]

Got same problem - please help!

[user-removed]

Same problem here 😞