I've just been through live chat and performed all the troubleshooting steps they have. I am not getting sound from the tv to the soundbar since I updated the TV to 1320 on Tuesday or so. Both are 2018 models.
I have a case raised but I'm hoping someone in the forum can provide a way to revert the firmware, or escalate to get this fixed.
Also, there was no release notes for 1320 released, even on the german forum that usually has it.