Stuck on Loading next hit - Failed to execute 'postMessage' on 'DOMWindow'

I use externalQuestion post my HITs. My webapp is hosted on s3 and served with a domain name and https using route 53, acm and cloudfront: https://movietitlecamp.com/?taskId=3

I tested the HIT with sandbox and everything works correctly. I can submit the hit successfully, load the next hit and retrieve the answer on sandbox. However, when I push it on production, workers cannot submit hit. After they answer, they got stuck in a page said "Loading next HIT...". I got this err:

console.log("The following error (Failed to execute 'postMessage' on 'DOMWindow') is expected, please do not report");
[
'https://worker.mturk.com',
].forEach(function(domain) {
parent.postMessage('{"assignmentId":"35GMH2SV3HA8EOV182JRDPV5F1QOEL","answer":{"taskId":"3","media_selection":"0","transcription":"Kingsman"}}', domain);
});

I'm sure my submit URL is correct. I appended the answer to the submit url as followed: https://www.mturk.com/mturk/externalSubmit/?assignmentId=35GMH2SV3HA8EOV182JRDPV5F1QOEL&taskId=3&media_selection=0&transcription=Kingsman

HITTypeId: 3EP32X463BXG5DPRWRT1ISC729P1HC
HITId: 3M7OI89LV0G1507PMCM0HHEM2CTC6H

Please help. I read most of the forum discussions but I could not figure out the problem!

Edited by: trinity19 on Jul 16, 2019 10:31 AM