PATCH Request to Zoom API results in "Invalid CORS Request"

Zoom Apps Configuration
Based on the Advanced Zoom Apps Sample - GitHub - zoom/zoomapps-advancedsample-react: This repository contains an Advanced Zoom Apps Sample. It should serve as a starting point for you to build and test your own Zoom App in development..

Details on your question, workflow or the problem you’re trying to solve.
I’m having trouble making a PATCH request to the Zoom Meeting API at (GET requests through my Zoom App work fine). Just like the reference app, I am using an HTTP middleware proxy to make requests in the backend. Moreover, I am able to make the request with no issues through Postman, so the access token, etc. are correct, but in the Zoom App, I keep getting “Invalid CORS request”.

403 Response and “Invalid CORS request”.

Troubleshooting Routes
The troubleshooting attempt types you’ve already exhausted, including testing with the appropriate sample app (found on Zoom · GitHub).
I’ve already tried adding 'Access-Control-Allow-Origin': '*', 'Access-Control-Allow-Methods': '*', 'Access-Control-Allow-Headers': '*' to the response headers, but the error persists.

How To Reproduce
Steps to reproduce the behavior.

  1. Start with the Advanced Sample App
  2. Create a server route and proxy endpoint to handle any type of requests to (make sure to pass the Zoom access token and content-type as headers to the proxy endpoint).
  3. Make a PATCH request from the front-end to the proxy endpoint. (logging the response returns a 403 error and logging the response.text() returns “Invalid CORS request”).