Debugging Cloudfront with multiple origins (S3 + API Gateway) : path pattern not working.

I have set up a cloudfront instance with 2 origins (frontend and backend) for a relatively simple SPA app with a KOA backend. When either origin is set as the default (*) behavior, it works exactly as expected. Whenever I add a second origin (i.e. path pattern /v1/* ), it fails to recognize the pattern and instead tries to load the resource from the default (*) origin. I can flip back and forth by just changing which the default is pointing at, and that origin works fine, but the second path is never accessed.

The precedence is
0: /v1/* , APIGateway (origin path = "/Prod"

1: default(*) , S3

calling xxx.cloudfront.net/v1/test gives me a blank page from the react frontend (i.e. I see all the metadata, and the same as xxx.cloudfront.net/nonsense).

calling xxx.cloudfront.net/ launches the frontend, as expected.

calling xxx.execute-api.us-west-2.amazonaws.com/Prod/test gives me "Hello World"

Currently in the process of putting a bullet in it and running two cloudfronts (and all the CORS headaches that entails)