The problem should be solved with plugin re-installation.
This is because PHP is currently working as CGI program on virtual host. To fix this log in to Plesk as admin. Edit service plan which is used by current website. Select tab "Hosting Parameters". Change "Run PHP as" to "Apache module".
Site.pro provides plugins from Plesk 12 (and higher) till Plesk Onyx.
To solve this problem please re-install the plugin on your Plesk server downloading new plugin from your license which you use on site.pro. It will return back your icon and title and the plugin overwriting should never happen again.
Please note that this action is absolutely safe - it will not affect clients websites.