Tooltip not working properly

I love this plugin. I have been searching for similar plugin from a couple of days and it perfectly fits my requirement. I’m going through the below page as I wanted to create a bubble chart. I have observed that tooltip is not working perfectly. Sometimes tooltip is not displayed even the cursor is place on the bubble. It is happening with most of the bubbles. Can you please lemme the solution for this? I wanted to buy this plugin though I have a feeling that it is little expensive.
https://www.ipublia.com/create-an-animated-bubble-chart-in-wordpress/

https://wordpress.org/plugins/ipu-chart/