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..

Description
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 https://api.zoom.us/v2/ (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”.

Error?
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 https://api.zoom.us/v2/ (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”).