Hi Paul!
Thanks for reaching out to us! Let me help you with this topic.
I can see the main events calendar showing fine in your site, so if you are using the shortcode in a page, it could be that the template you selected for that page is conflicting with the tribe bar.
Could you please try selecting a different template for that page and see if anything changes? Let me know about it.
Also, please share a link to that page so we can have a closer inspection and see if we can find the problem.
Thanks,
Victor