There are 2 issues with the Helix template
1. Bootstrap 4 has changed the coding of the popovers that we use - I have a fix for this. Replace the file components/com_jevents/libraries/bootstrap.php with the attached file
2. The popovers in Helix are placed at the bottom of the page despite following the syntax at
https://getbootstrap.com/docs/4.0/components/popovers/ to the letter which suggests a CSS issue with this template.
As Tony says we are working on a platform independent solution since multiple versions of Bootstrap and UIKit, combined with template CSS idiosyncrasies make universal support of this functionality very difficult at present