Creatomate renders blank MP4 when triggered via Make.com (audio + image URLs not applied)

:bullseye: What is your goal?

Automatically generate short MP4 videos using Make.com with OpenAI (text + TTS), Pexels images and Creatomate, then save the final video to Dropbox.

:thinking: What is the problem & what have you tried?

The scenario runs successfully and Creatomate returns a render URL, but the resulting MP4 video is invalid (blank video).

Symptoms:

Video has correct duration (~9.5s)

No image

No text

No audio

Dropbox and media players show “MP4 compatible, but something went wrong”

What I’ve tried:

Verified audio MP3 (generated by OpenAI TTS) is valid and accessible via public Dropbox download URL

Verified image URL (from Pexels API) opens correctly in browser

Template works correctly when rendered manually in Creatomate editor

Tested with:

Only Modifications (no Extra Modifications)

Hardcoded URLs

Minimal fields (Image, Text, Voiceover only)

No errors in Make scenario except sometimes “Response marked as invalid” from Creatomate

Suspecting an issue with how Creatomate handles external URLs (audio/image) when triggered via Make.

:clipboard: Error messages or input/output bundles

Creatomate - Render a Template
Error (sometimes): Response marked as invalid
Other runs: no error, but generated MP4 is blank