Having a slight sound issue with the Sony VTX D800U freeview box but only on radio channels

When a radio channel is selected it starts to play the audio but after a few seconds it cuts out the screen goes blank and then another screen shows up but still no audio.
This seems to happen on all radio channels, below is a short video that shows whats happening
https://youtu.be/YdOjB3uSy_M
You can get the audio back if for instance you enter the menu system of the box but as soon as you exit it and go back to the plain channel you lose the audio again
