This can happen if you are using GD Rating System Pro additional addons (like Multi Ratings or User Reviews addon). If that happens, make sure to disable GD Rating System Pro and all addons for it, and upgrade main plugin and all its addons, and reactivate them after the upgrade is done.
All Dev4Press plugins and addons require jQuery. But, they will work only if the jQuery is loaded with the WordPress proper Enqueue method. If you are replacing jQuery that comes with WordPress with some other version loaded from other location, my plugins will not function properly, and that goes the same for most of the other WordPress plugins that depend on the proper way for loading jQuery.
This is always the issue with the page cache. The plugin supports the use of cache plugins, but in that case, it needs to get current ratings through AJAX to avoid showing old cached page. The plugin includes Dynamic Load addon that will load rating blocks through AJAX. This addon is disabled by default, and if you use cache plugins, just enable this addon from plugin Settings -> Extensions panel.
Whenever you update the plugin, make sure to clear all cached data from cache plugin, server-side cache, CDN and finally browser cache.
Alignment for complex HTML elements can be a very tricky issue, and it largely depends on the container and styling it has. The plugin has options to add alignment classes to the rating block, but, these classes don’t include actual styling and they are meant to be styled individually for the theme used.
To center element, that element should have the width set. But, if you set width for the rating block, that block will no longer be responsive. The plugin automatically makes stars smaller for the rating block to fit the current screen with. Having fixed width set for the rating block will prevent the plugin from making it responsive.
You can use CSS for responsive breakpoints to set different widths, but that too depends on the theme (themes usually have different breakpoints and different grid systems), and it is best to style rating block alignment for each individual theme to make sure alignment works for your theme. Also, depending on the theme and the grid system use, there might be some other way to center elements.
Plugin alignment feature is only placeholder class name, styling must be defined for theme.
If you don’t see stars, but instead there are letters S, this means that font with icons used by the plugin is not loaded by the browsers. The reason for this is that most likely your website is loading a font from CDN and some browsers are enforcing CORS policy. To get more information about it, and the solution on how to fix it, check out this article: Loading fonts from CDN.
Make sure GD Rating System settings are correctly set for rich snippets usage. After that, you can use Google Structured Data Testing Tool.
GD Rating System is adding fully functional and standardized rich snippet for rating or review, and you can test all your posts to confirm that rating snippet is correct. But, there is no way to influence Google to show the snippet inside search results. There is no way to know how, why and when Google displays rich snippet and even the big websites like IMDb or Amazon very often don’t have the rich snippets displayed.