Opener only opens one door

Discussion
1

Hello everyone,
I have installed the Nuki Opener, Bridge and the Smart lock.
Almost everything works, only the opener behaves strangely in the “RING TO OPEN”.

We have 2 entrance doors downstairs in a 5-storey building, which I can open upstairs with the same button.
I can open both manually, but “ring to open” only opens the inner door, waiting there and ringing more times does not help.

What could be the reason for this?
The Opener is connected to a Siedle BTS850-02

Thank you for your help.

2

UPDATE:

I have completely reconfigured the opener, and have gone through the setup with the 2nd lower door.

Result:
I can open both doors on the intercom.
In the app, I can open both doors by hand.

Ring to open now only opens the outer door, the inner door does not receive an open signal.
Before that, only the inner door worked.

I conclude from this that it only learns one doorbell signal, the second is structured differently and is therefore not understood as an open command.

What ideas do you have?