AMP pages valid, but only load if I add ?AMP to URL

Replies: 1

I am building a site using Enfold theme. I use Yoast SEO plugin, Amp for WordPress and Glue for Yoast SEO & AMP. Generated AMP pages are valid when I test in Google AMP test, but when I open the site on mobile, I see regular web site.

Only if I add ?AMP to the URL, then I see the AMP page. What could be the problem? Aren’t they supposed to be shown by default on mobile?