Page Messages for Newsletter Email Subscribe/Unsubscribe Not showing

I am using a third party theme (RokanThemes Clickbuy) and although I can see the addSuccess/addError when I inspect the page, no actual page message is displayed to the user when they click on newsletter links within their email to confirm success or an error. Which pages would be a good place to start to look for any omissions, errors etc? Cause it looks like the correct output is written to the page just nothing showing. I’ve included a screenshot of the inspector code, sorry can’t figure out the formatting for the injection of code here..

Screenshot of html code