Custom Rewrite Rules doesn’t work!

Hi,
I’m trying to make a custom rewrite rules but this new rules doesn’t work!

I’ve installed the Internal Rewrite Viewer plugin and also the simple rewrite of this plugin doesn’t work.

This is the url of plugin: https://www.dagondesign.com/articles/wordpress-internal-rewrite-viewer-plugin/

This is the rewrite url that doesn’t work: https://www.wiitalia.it/rewrites/

You can see my rewrite rules by this url: https://www.wiitalia.it/?showrewrites=1

As you can see there is a rule for the plugin:
[rewrites/?] => index.php?showrewrites=1
but it doesn’t work.

Anyone can help me? Please, I’m working on this from weeks and I still had no result ??