Google ad was preloaded using link preload but not used within a few seconds from the window's load event

Question

When I go to my website no ads are displaying even though I set one at the bottom of the page. It returns error - The resource https://pagead2.googlesyndication.com/pagead/js/r20181107/r20180604/show_ads_impl.js was preloaded using link preload but not used within a few seconds from the window's load event. Please make sure it has an appropriate as value and it is preloaded intentionally. Yes, adblocker is disabled Here's my code for ad:

<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
<ins class="adsbygoogle"
     style="display:block; text-align:center;"
     data-ad-layout="in-article"
     data-ad-format="fluid"
     data-ad-client="ca-pub-9121789382833091"
     data-ad-slot="8487804504"></ins>
<script>
     (adsbygoogle = window.adsbygoogle || []).push({});
</script>

Answer 1

I suspect this is not the reason why ads doesn't show because after a few hours without updating the source code of the page the ads finally display, but the warning is still here in the javascript console.

I've noticed that every time I'm updating the source code, the ads disappear again for a few hours so I guess Google doesn't really "trust" me and ads are automatically suspended till a bot or something comes back to check that everything is OK.