This is the email I received from Wolfgang:
I manage a site where we have installed your plugin on the site and we have the pro-version. Since the last petition the plug-in is not working properly anymore. All the signers are not refreshing. It’s only refreshed when I log in to the wp backend. What problem we have here?
In the past I have found this is caused by caching of your site.
This isn’t the place to explain caching, but if it is the problem the solution is to go into the caching plugin settings and exclude the page that has the petition on it so it is no longer cached.