No sound on playback on TV

Hi There.

Device = Tablo 4 tuner, Model SPVR4-01,
Firmware version 2.2.38
Sony Bravia TV
All connections are HDMI

The sound recently stopped working when playing back TABLO recordings on our TV. Both old and recent recordings.

This seems to have coincided with the install of Bell Canada Fibe TV 4K DVR.

The sound is there on live shows. The sound is there on playback on my PC in a browser.

It used to work with Surround Sound 5.1 on and now doesn’t work at all both on and off.

Yes I have rebooted the Tablo. does it need to be rebooted after turning off SS 5.1?

TIA

Horray. The sound came back on the recordings made on the 25th, Don’t know why but am happy they are back.