Studydocuments upload fails

When trying to upload any studydocuments with the upload form, the process fails because the API responds with an error 422.

The API response has the following content:

{"_status": "ERR", "_issues": {"files": {"0": "must be of media type"}}, "_error": {"code": 422, "message": "Insertion failure: 1 document(s) contain(s) error(s)"}}