Plugin don’t works in multisite

I have a multisite installation. The plugin works fine in the main site but in child sites don’t. Every time I create a new snippet, the system notice “PHP Snippet successfully added.” buy the list stills empty (PHP Code Snippets not found) and the shotcode don’t works either.

This cannot be “plugin or theme interference” because it works in main site with all other tested before plugins ans theme.

I am willing to buy the premium version, but I need to be SURE the plugin works in multisite.