In the previous releases I could select a song as source for radio playing.
That seems no longer possible, while I really liked that feature. Now it just randomly seems to pick any song to start with?
This was called Seeded Radio, and the feature has indeed been removed. There has been a running thread on this on the Beta builds... I too am very disappointed to see this feature go, but there has been no word (one way or the other) on if it will be back.
I sure hope so, because that was the main way I used the Radio!! It was very nice to be able to select a specific song, hear it, and then just have the radio take over. If you wanted to hear another specific song, you could just send that file to the Radio and when it was done, the Radio would take back over.