Hi there,
I changed the template to Cassiopeia for that specific page and the Grid module is working fine.
Changed it back to your template and it stopped working. This means that the problem is caused by the template that you are using.
I see a JavaScript error in the console:
Uncaught TypeError: $ is not a function
This error is usually caused by a jQuery incompatibility.
Does your template support jQuery? If not, try installing the jQuery Easy plugin and set it up to load the latest version of jQuery.
https://extensions.joomla.org/extension/jquery-easy/