Custom GET parameters not consistently visible in Google Analytics

I want to track custom GET parameters with Google Analytics. I don’t want to create anything inside the GA account (UTM and the rest of it). I’ve added this to my code:

<script>
    (function(i,s,o,g,r,a,m){i('GoogleAnalyticsObject')=r;i(r)=i(r)||function(){
        (i(r).q=i(r).q||()).push(arguments)},i(r).l=1*new Date();a=s.createElement(o),
        m=s.getElementsByTagName(o)(0);a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
    })(window,document,'script','//www.google-analytics.com/analytics.js','ga');

    ga('create', 'xxxxxxxx', 'auto');
    // set of parameters tracked
    ga('set','parameter','value');
    ga('set','anotherparam','anothervalue');
    ga('set','customparam','customvalue');
    ga('send', 'pageview');
</script>

This was tested simply by visiting

www.mysite.com/somepage.html?parameter=value

Or

www.mysite.com/another-page.html?anotherparam=anothervalue

etc.

After opening links directly, and checking GA dashboard / panel at the same time, the links were visible in the Realtime section. However, not all of them were visible inside Acquisition or Behavior parts of GA dashboard. As far as I can tell, there are no patterns to when the landings are detected (the links are opened on both a desktop PC running Windows, and Android phone via Google Chrome, sometimes they are visible, other times they’re not visible).

Finally, my question.

How can I capture page landings with a custom GET parameter, without the UTM tracking codes? Can it be done through my JavaScript code alone? I do not want to create custom dimensions and custom definitions inside Google Analytics.