The latest update to the extraction engine (ealy December) has removed the ability to access the audio streams on the BBC iplayer radio section. The protocols displayed only have MP4 listed and no longer give access to MP3 or M4a streams. This means that the quality is reduced to 128kpbs which is useless for classical music.
I have an older laptop which has not been updated and the streams are still visible and available, so the latest update seems to have created the problem. I hope this can be resolved soon. I have reinstalled the program without success and I am running in Windows 10.