I have installed Oracle APEX locally on my Mac using the Docker scripts from https://pretius.com/blog/oracle-apex-docker-ords/.

I set up the network ACLs in the FREEPDB1 PDB to allow APEX_PUBLIC_USER and my parsing schema (SWIFTCARE_APP) to connect to api.openai.com:443.
In APEX I created an HTTP‐Header credential (“Open_AI”) with:
- Header Name: Authorization
- Credential Secret: Bearer sk-…
- Valid for URLs: https://api.openai.com/v1/*
Then I configured a Generative AI Service using that credential. However, when I test the connection, I am getting following error:

Also when I run:
DECLARE
l_response CLOB;
BEGIN
l_response := apex_web_service.make_rest_request(
p_url => 'https://api.openai.com/v1/models',
p_http_method => 'GET',
p_credential_static_id => 'Open_AI'
);
DBMS_OUTPUT.put_line(l_response);
END;
ERROR: ORA-29273: HTTP request failed
Curl from inside the container works (returns HTTP 200 when I include the same Bearer header), so I know the key and network are fine. What configuration step could I be missing in APEX so that MAKE_REST_REQUEST still fails with ORA-29273?