when i first started using spotify, right clicking on a song and selecting 'play song radio' would take me to a playlist of song based on that song, and it would include the song i had selected.
now when i go to a song radio the base song is no longer their which is really frustrating.
Updated on 2019-07-20
This idea is now implemented, so if you start Radio on a specific song it'll appear at the top of the playlist. Be sure to keep your app up-to-date to have the newest features.