Email Notifications not working

I have the pro version of the plugin. The notifications are not working in the forum when members submit new topics or new reply.

I had a look into the forum plugin settings: Forum > Settings > Email. The message body in both new reply and new topic is empty.

When I go to add the tags and click 'Save changes', the changes are not saved and the message body is empty again.

I have attached a screenshot.

Please advise.