Troubleshooting [pdb_record] shortcode

I’ve been using this plug-in with the twentyfourteen template for about a month. For some reason (my fault, no doubt) the link from the [pdb_list] shortcode to the page that contains the [pdb_record] shortcode has stopped working. I’ve tried most of the troubleshooting tricks listed in this forum, such as uninstalling and reinstalling the plug-in, disabling all other plug-ins, etc. No success so far.
I’ve even tried using a direct link to the page with (http://localhost/index.php/rider-details/?pdb=63) but that doesn’t work either.
I’m at the point where I’d like to try tracing what’s going on in the plug-in so I can see where the problem may be lurking. Since I’m relatively new to WordPress, could anyone suggest an approach to troubleshooting?

Sincere thanks!

https://ww.wp.xz.cn/plugins/participants-database/