Hi intrepidtrinity,
I just took a look and unfortunately, I do not think that this is an issue with HD Quiz – your site has a ton of script errors and is not correctly loading content. This is not something I can fix for you, but I can at least try and point you in the correct direction.
First: Clear your site cache (You are using WP Rocket). Sometimes page cache plugins can create corrupt caches when another plugin is using broken scripts. Clearing the cache will force it to try and recreate a fresh cash.
Second: The default WordPress debug steps. Start by temporarily switching themes to see if the problem persists (you can actually preview your theme to test). If the problem is gone, then we know the issue was caused by your theme.
Third: Disable all plugins except HD Quiz and verify the problem has been solved. Then re-enable each plugin one by one until you find the one that is breaking the site.
Last: Elementor. Sometimes when upgrading elementor, it breaks certain shortcodes and layouts. Test by creating a NEW page and adding a quiz shortcode. If it works on the new page but not the old, then we know the issue was elementor. The solution would be unfortunately to recreate each of the pages again.
Ok. Did you try the first three steps?
