Hi Jerry,
I logged in and found two issues actually. One was the results container width settings. You had a 50% and 60vw setting for mobiles and tablets. While these are okayish for most cases, in your setup is not going to work, as the plugin container is in a sticky header element, which is in a fixed position, so snapping the search results to the container will be very problematic.
For now I have changed them to 480px and 320px values. Those should work much better.
The scrollbar is not working, because there is a javascript issue thrown on the main javascript console, and is caused by some sort of a script “cmbv2.js” – which seems to be conditionally loading the plugin scripts, but it fails, and it also does some extra code incjection, which does not work whatsoever.
It looks like it is related to a cache minify of some sort maybe. If you turn that off so the scripts can load normally, it will then properly load the scrollbar script.
When I am logged in, the issue is not present and everything works okay, so this is only configured for visitors, and not logged in users – not sure if that helps.