You won’t hear any sound on RECORDED SKY PROGRAMS, assuming the optical cable is plugged into your Sky Q box.
This is caused by Sky’s intention to restrict the possible uses of it’s Q box.
The sound output is not the same for recorded / paused TV. When recorded / paused the optical output of the Sky Q box is not active so the sound would need to be collected from a different location (i.e. from the TV etc. ).
The only way around this is to have 2 optical cables sitting next to your TV Link, OR get rid of Sky TV…