Uploading File via API - "Missing Parameter" even though parameters match

Hello, I am trying to upload a file via API, currently using Postman to test, eventually from an external app. In Postman, the file is under the “returned_file” key, same as what is set in my workflow, but Bubble is giving me a “missing parameter” error. Any ideas what I’m missing? Screenshots below



The file datatype is for Bubble internal files that already exist.

Bubble apps have a built in endpoint where you send the Base64 data and the file name to upload it:

Public file:

Private file:

these screenshots are from a ZQ plugin to upload files: Bubble Plugin Editor - Base64 File Uploader & Downloader