Oh, God! you are not only expert but also great story master, and you are the only one who make me fully understand JS 
Really great thanks.
To make sure it will work for me, I put something into scene and change one of button to be more recognized in mobile mode:
As screenshot show, it works fine in local, but the buttons still does not show up in Wordpress, FYR, I am using the HYPE official wordpress plugin at Tumult Hype Animations Wordpress Plugin
I deactivated any of optimization plugin to track this issue, but still can not fix it.
It would be highly appreciated if you or anyone could help here, please access this page for check at https://www.lovcour.com/scroll-test
and here is attached hype document, thanksstickmenutest_mhv1.hype.zip (55.4 KB)
Alex