403 error when submitting form for authenticated users.

Problem/Motivation

When an authenticated user attempts to submit a form I'm getting the following error.

Error submitting FORM NAME contact form. Error: Request failed with status code 403.

Response message: X-CSRF-Token request header is missing

Submissions are working properly for anonymous users. I've attached screenshots of the REST resources and modules permissions settings. I've also attached a screenshot of how I'm submitting the post request.

I see this issue → which seems similar except that they are having issues with submissions for anonymous users while I'm not. I'm only having issues for authenticated users.

Steps to reproduce

1. Install and configure the module.
2. Attempt to submit the form as an anonymous user. It should succeed.
3. Attempt to submit the form as an authenticated user. It should give the error from above.

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes