I would try hitting the URL that it is using to generate the report directly and logging in with the credentials you're using in the plugin to see if you can access the report that way to see if it's a plugin issue or permissions (or possible something else) related. If you turn up the logging on the plugin it will probably show up in the logs.
Are you saying that by hitting the report url directly you are getting an empty report? Support can't really investigate issues with community plugins but if you are able to demonstrate that the rest call is at issue they may be able to look at it. If you did try, what report call does it look like the plugin is making?