I guess it could be down to poor channel settings. Maybe audio details have changed from what you think they are.
Have you done a manual rescan ?
Check the plugin AudioSync if you have it.
Sometimes this plugin makes delays in AutoMode on some channels, wich can produce a failure to the sound of it.
What channel is this ?
it has NO SOUND
problem at T.TV
press Yellow Button
1 MPEG x
Yellow Button = subtitle
what about sound ?