Thanks for coming back. Has happened when turning the TV to standby after watching Channel 5 HD today. On switching the TV back on after a delay of approx 3 hours, there was no sound on Channel 5, but after changing channel to BBC 1 and back to 5 again it was ok.
The audio setting on the TiVo box is set to ‘Dolby Digital to PCM’. There is no sound bar connected.
The TiVo box is connected to the Tv by a HDMI cable