Problem with Pagebuilder templates

I’ve inherited a Wordpress site using the Sport theme from ThemeCanon. Many of the pages are built using the Canon Pagebuilder. My problem is with the display of the Pagebuilder Template dropdown list under the Sport Page Settings panel when building pages based on the Pagebuilder template - in brief, it doesn’t display.

Inspecting the page source shows that the dropdown list has been built correctly but it has the class “default_hidden” which is why it isn’t visible.

I traced this back to plugins/sport-core-plugin/inc/functions/functions_cmb_pages.php, where the contents of the dropdown list are built with the “default_hidden” class (among others). A number of other elements are also built here using the same class.

I presume there should be some trigger for the default_hiddden class to be removed later, so the dropdown list can be displayed?

I have used a workaround by deleting the default_hiddden class from the list of classes for the dropdown list in functions_cmb_pages.php but would like to know if there is a “proper” fix for this problem.