Flexslider not loading when viewed from phone, how to fix it?

Question

AJAX

There is a WP site that implements ajax loading of the content (all content) of pages and posts in a modal window instead of going to the page itself from the directory. Everything was done according to this lesson.
Loading pages have a gallery with flexslider. In the mobile version, the pages themselves are loaded perfectly into the modal, that is, the contents of the additional fields are displayed perfectly, but the flexslider does not want to load pictures in any way. And I can’t even see what the problem is: either the additional fields with the “Gallery” type do not want to be loaded on a mobile phone, or the slider does not want to be loaded, and therefore the pictures themselves remain invisible.
In general, there was a problem with the slider due to Ajax content loading, but it was solved by initializing the slider in the success function in the Ajax request. But why the problem returned on mobile devices is not clear. The catalog
page itself .
PS The question is in the "ajax" section, because it is in it that the problem with the slider most likely lies.