My Sony TV KD-55AF9 does not output sound on its SPDIF socket. Why is this & how do I fix it

[geocar.finch]

How do I check that the TV itself is running up to date Software?

[rooobb]

Help remote Button will show on the top right  corner actual version 

[Joe_Dohn]

The latest version is currently v6.3626, and here's the link from the Sony website: https://www.sony.co.uk/electronics/support/oled-tvs-android-a9f_af9-series/kd-55af9/downloads/000167...