I am unable to GET, PUT and DELETE variables through the /2.0/repositories/

{username}/{repo_slug}/pipelines_config/variables/{variable_uuid} endpoint. Whatever I do, I get a 401 Unauthorized response.

However, GET /2.0/repositories/{username}

/

{repo_slug}

/pipelines_config/variables/ DOES work, and i can see two variables being set.

I have the following permissions:

Repositories: Read, Write, Admin
Pipelines: Read, Write, Edit Variables

I am using Oauth 1.0 authentication using the Authorization header. Using Postman and a PHP library (Bitbucket\Api) are getting the same result.

Am I doing something wrong or is this endpoint buggy?