A current problem with sound on playback of radio recordings (both old and new) has been acknowledged by YouView and they expect to address in a future software drop. BT and YouView support should be aware of the issue.
Two potential work rounds seem to exist one is whilst starting playback of the recording is to press the YouView remote power button off and then back on again. the second is again whilst playing the recording s to remove and then reinsert the hdmi connection between the Youview brand the TV.
So the good news is your recordings are there and new can be made but listening to them can be a chore currently.