Hi @SMW Sorry you are having a problem with the sound on BTTV. As you are getting 140mb you are on Fibre To The Premises (FTTP). Do you know if the engineers that visited were broadband engineers or BTTV (Qube) engineers? It could be a fault with your broadband service that is causing the problem with the BTTV.
This is an ongoing problem with programs over the internet. It would seem to be a BT transmission or Youview box problem and is not related to the BT Hub as it also occurs when using a third party router. As many have found the only way to overcome this issue is to momentarily pause then replay the program you are watching. It is about time it was rectified as it has been ongoing and reported here for months now.
Sound can be lost if there is a timing issue between the BT YouView box, and the TV. This can often be fixed by dropping the output resolution to 1080i.
@SMW has not said whether this affects just Internet delivered channels, or FreeView as well.
In that case, its more likely to be a compatibility issue between the BT YouView box, and the TV.
I had a similar issue with my old TV.
Can you please check what the HDMI resolution is set to, on the BT YouView box, its on the settings menu. under the 'TV Signal & Quality' section where the bottom but one option is 'HDMI Display Settings' It will be one of these values.720p, 1080i, 1080p
Is the BT YouView box directly connected to the TV using a HDMI cable, or does it go via another device?