Hey William,
Thanks for reaching out!
Unfortunately, what you describe here means that your custom theme is the problem:
When I change the subject to fourteen , the tooltip back to work.
We unfortunately cannot help fix themes, so if you bought your theme from somewhere online, definitely reach out to their customer support team for some assistance. I found these specific JavaScript errors on your page, all of them arising from the theme (or from other plugins on your site):
Error: Bootstrap's JavaScript requires jQuery
TypeError: document.getElementById(...) is null
TypeError: $ is not a function
Bring these issues to your theme author and see if they can help—I hope they can!
In the meantime, Events Calendar Pro is at version 4.1.1 now. I would recommend updating to that here, too. 🙂
Thank you,
George