Conflict with Formidable module

When using Formidable module to create a form with input files, the uploads does not work if we have S3 Uploads enabled on the WP. There are unfortunately no errors message, the ajax request stay in pending mode and eventually fail without response.

Formidable input file uploads works fine if we disable S3 Uploads.

https://formidableforms.com/

I have reached out to Formidable support and they say they can't do anything and that I have to try to contact S3 Uploads dev...