Complaint of no category id, but I am providing it

I am using the v1/comany/documents API to upload documents. When I try I get the error message "Failed request to Personio - Bitte geben Sie category id ein, um fortzufahren." I am supplying a category id retrieved from the v1/company/document-categories. I am sending the request as multipart/form-data with the correct header.

Here is the form data I am sending with my request (encoded using FormData):

[ 'title', 'Resume.pdf' ],
[ 'employee_id', '27198334' ],
[ 'category_id', '990489' ],
[ 'file', {filedata} ]