I didn't have any issues having Cortana to tell Spotify to playback songs in the past. Just recently, on all my Win10 PC's (version 1903) when I tell Cortana to play a song, it identifies the song, then says "And now, playing.... on Spotify", then launches the Spotify UWP app (and even the Win32 version on a couple of my other PCs).. but the app just sits there doing nothing.
It looks like Cortana is sending a playback request to Spotify and even launches the Spotify app... but that's it. I have thrown everything and the kitchen sink at this issue.. It doesn't seem like the issue has anything to do with the Spotify apps. It's either Cortana's back-end service or Spotify's Cortana app link connector.
I already tried everything suggested in the below link:
I even changed my Spotify password. So... what more do I have to do (besides all the items discussed in the link above)?
Hey there everyone,
Thanks for your patience this far!
Our tech teams have done their magic backstage and this should be now fixed in the latest version of the desktop app.
If you're having troubles, make sure to try a clean reinstallation of the app following the steps in this Spotify Answer. If that doesn't do the trick, let us know in the relevant Help Board and we'll be happy to lend a hand there.