How can I create a new azure function in Azure portal without getting the error: "Error while loading - Error retrieving function"?

Question

I created a new python Azure function app, which is up and running. (Using the Consumption Plan)

When I try to create a new function in Azure portal, I can go through the configuration steps and get the notification, that the function was successfully created.

After the function is the opened in the Code+Test tab, I get an Error: Error while loading - Error retrieving function.
When I exit out of the function, it is not listed in the function app. There is no function available again.

I have another function app running with the exact same configuration. It works like a charm.

Any ideas how to solve that issue?