CORS issues when invoking functions via browser

I am following the examples at https://supabase.com/docs/guides/functions#cors-cross-origin-resource-sharing to try to make a simple function invocation from the browser. However, I get CORS errors despite passing in the correct headers. The out-of-the-box example found here https://github.com/supabase/examples/blob/main/supabase-js-v1/edge-functions/supabase/functions/browser-with-cors/index.ts just does not work.

Any help would be much appreciated.
KP

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