This can be child theme issue on your site so to confirm it just temporary use the Shapely theme instead of child theme on your site. If everything works fine then it’s your child theme issue so just share me your child theme so that i can troubleshoot it.
Unfortunately there are many issues in your shared child theme and we have to develop custom code to fix it.
Developing custom code for custom functionality is beyond the scope of support that we provide here.
If you are not a developer then you can consider hiring a developer to develop it for you. You can hire a developer from any freelance site. Colorlib recommends the developer https://www.upwork.com/freelancers/~011652ffec8865c6d5