OAuth2 API Integration seems accepted, but no keypad codes created + redirect URI can't be saved (500 error)

Discussion
1

Hi everyone, :wave:
I’m new to API integrations, and I’m trying to automate keypad code creation for my guests using the Nuki Web API and a Google Apps Script.

:white_check_mark: OAuth2 seems correctly configured:
I followed the documentation and successfully obtained the access token via my own redirect URI (hosted on Netlify). The token is refreshed properly, and my API requests are returning HTTP 200 or 204 responses without errors.

:repeat: However, when trying to create a type: 13 authorization (keypad code) for either of my two Smart Locks, no code appears in the Nuki app or on web.nuki.io.

:heavy_multiplication_x: Additionally, on the web.nuki.io interface, I cannot save the redirect URL in the API section — it throws a 500 Internal Server Error. Could this be related?

:lock: My goal: Automatically generate a 6-digit code (based on the guest’s phone number) and assign it to both locks when a reservation email arrives.

Has anyone else experienced this issue?
Could the fact that the redirect URI can’t be saved be blocking the API in some way?

Thanks a lot for any help or guidance! :pray:
Fred