My Release Radar playlist also became shuffle-only again yesterday, but Discover Weekly and Daily Mix playlists are working normally for now. I hope this is a bug and they are not slowly reverting what they granted the free users.
Thanks for reaching out to us about this, and apologies for the late reply!
If you're on Spotify free on mobile, you will have several playlists which you can listen to on demand. These include some of the most popular curated playlists on Spotify, such as RapCaviar, as well as personalized playlists like Daily Mix.
You can't choose which playlists are on demand, but Spotify will include a few editorial playlists that align with your taste. These may change over time.
Hope that clears things up! Let us know if you have any further questions regarding this.
@Unbeknownst - could you let us know if your Release Radar is still shuffle only? If so, we can look into this.