I created a HTTP request scheduler that allow people to setup rule based notifications: https://ihook.us. Not making money yet, all free plan users right now :)
wow, thank you so much for spending time to post the issue, really appreciate it! I thought this issue had been resolved months back by adding CORS rules on the CDN (S3). I wonder the error is due to the updated policy somewhat not pushed to some edge. Just tried to push the policy again and hope that helps.