This appears to be down to Samsung's latest firmware release, which is version 1020.7. There have also been reports on the company's community forum of similar issues with the HW-Q800D and HW-S801D soundbars, but in fewer cases.
I spoke to customer service of Samsung UK and they are pretending that they are not aware but apparently they are investigating 😂😂😂. They arranged a service for next week as a normal mechanical repair. Maybe someone is coming with hammer 🔨 and screwdriver 🪛.
Advanced I have asked for refund as it will probably take ages to resolve this problem. Samsung as usually will try to blame customers that they updated wrong software, not following the instructions etc.