Ubuntu Touch without sound on Fairphone 4

[stephan-addi]

Fairphone 4 - Ubuntu Touch - Linux Phone.pdf
After I carried out the installation on my new Fairphone 4 last night, I was very enthusiastic at first. It seemed like everything was going very smoothly. This morning I found that the complete sound: headphones, speakers, microphones and volume controls are not activated.
Although it is on
https://devices.ubuntu-touch.io/device/fp4/
is called:
=> "Fully Optimized State: Supported by Device Maker!"
(see attached)
I made a new installation on my new Phablet Fairphone 4 three times today. Now I'm at a loss.
Please help me!
Best regards
Stephan