Connection and synchronisation problems MMI 2 high BT

Hello, I have set the BT for telephone in my Audi A6 C6 MMI-2 high.

MMI runs on the latest version 55.70.

I have a Samsung S24+ but cannot perform a synchronization with the calls and contacts. I see a BT connection (paired) on my phone and the BT logo is on the MMI.
I have given permission for access to calls and contacts on my phone. In my previous Audi A6 the BT icon only appeared when I put the phone on BT, now the icon is constantly on. I can not call anybody, even my phone sais the phone is connected to the MMI BT.

The MMI says connecting... and then a little later at the top: user not.... but I cannot read what exactly is written afterwards, because the text disappears at the edge of the screen.

I have also done a factory reset of BT and deleted all devices, but no result.

Read the phone with VCDS 77, but cannot find any problems. I also do not see any profiles of previous phones or users that I could possibly delete.

Does anyone have an idea what this could be?
I would like to hear it. Thank you in advance!