From what I can tell on your site, your template is redefining the Javascript function "dropdown", which is overwriting the Bootstrap Javascript function we're trying to include and use. The file that looks to be redefining it is:
templates/yoo_capture/warp/vendor/uikit/js/uikit.js
Is there a way to disable that Javascript file from loading, even temporarily, and see if that lets the dropdown function properly? If so, we should be able to help you work around that, but we'll need some confirmation first.
Thanks,
Alex