Congress.Gov API_KEY_UNAUTHORIZED

[Flipersome]

I signed up for an api.data.gov API key to access the Congress.gov API, but I'm receiving a 403 "API_KEY_UNAUTHORIZED" error for all Congress.gov endpoints. Do I need extra approval?

"message": "The api_key supplied is not authorized to access the given service."

I tested it in the official Congress.gov API documentation interface at https://gpo.congress.gov/#/member/member_list - all requests return the same 403 error.