Not working anymore

Could you post your site URL here, so I can have a look?

Here it is:

https://lnx.sinapsi.org/wordpress/

I add this code into the Custom Ads field:

<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
<script>
  (adsbygoogle = window.adsbygoogle || []).push({
    google_ad_client: "ca-pub-5512977131162511",
    enable_page_level_ads: true
  });
</script>

The weird is that if I check:

https://lnx.sinapsi.org/wordpress#googleads

then it works, but the

https://lnx.sinapsi.org/wordpress/

not shows any ads.

You seem to be using a combination of different ad plugins on your site, and some of them display ads on both desktop and mobile. I’d recommend against using my plugin, or you’ll have too many ads per page as per Google’s guidelines:
https://support.google.com/adsense/answer/1346295?hl=en#Ad_limit_per_page