problems with recruting api /johnbaker.personio.de

Hello
I received the api key from my personio login. There seems to be an issue:

If I try it on your dev-page it doesn't work

If I deliberatly send a wrong api-key I get a formatted error message. But If I try it via postman I get a blank response and it's marked as 401.

Thanks for letting me know if I'm doing something wrong,

kind regards

Robert