Phone Verification fails after receiving Zoom-Code

Hello, I am trying to register my mobile phone number in my profile, using the URL  https://zoom.us/profile.

The full number itself is already registered as the 2FA method.

Registering it as 2FA number five, ten minutes ago went without a hitch.

This time, though, when I enter the Zoom-Code, I get a message that the phone number could not be verified.

I have tried both version of number notation, and even got Codes using either method for the international phone number format, delivered to my mobile – but those always result in a not verified message. What can I do?