Hello:
I have diagnosed the problem and found what appears to be a solution.
The plugin Admin Settings page appears to set the default “Plugin Admin Access Level” as “Admin” which is not a default WP user type anymore. WP appears to be using “Administrator” as the primary admin user type.
Furthermore, we use Administrator as a SuperUser status and created a webmaster user type that uses “Admin” as a user type. The webmaster is basically a normal WP administrator but cannot admin plugins or other key settings.
When uninstalling the participants-database plugin, it does not fully remove itself from WP. We found it left the database files and finally after a lot of searching we found a residual trace of the plugin named “pdb-default_options” in the database table wp_options.
The corrupt privileges setting are stored in this field. It was NOT deleted when the plugin was deleted. When the plugin was re-installed this option was not overwritten and therefore the problem re-emerged.
After removing that option from the wp-options table and then re-installing the plugin we were able to access the full menu of options and settings for the plugin and it now works again… although we have NOT attempted to change the “Plugin Admin Access Level” or any other Admin Settings.
We found NO other plugins interfering with this plugin although other plugins that allow for or create custom user types might cause problems.
I would like to suggest that the delete function also remove the “pdb-default_options” from wp_options table. Also a reset to default status would be nice.
We will do some additional testing going forward and will likely use the plugin in a separate WP install so as to not cause issues with the main site.
Overall we appreciate and commend you on the plugin. It is a very nice plugin. Thank you.