jQuery Ajax not working in iOS (with list.js)

Found a feature that’s not working on our website — but only on iOS devices (iPad, iPhone).

We’re using list.js to do a live filtering of a directory based on what’s typed in an input. There are also two select fields that allow for filtering based on taxonomies. These work fine.

The live-filtering feature works in Chrome, Firefox, Safari, IE and Android. I’m not sure where to go next for debugging, as we’ve done the following to no avail:

• Checked to ensure no upper/lowercase file names and/or paths that could trip up iOS.
• Added a console.log to the ajax code to make sure it’s firing on iOS (it is; verified by Web Inspector via Safari).
• Checked for errors or warnings via Web Inspector (no errors, no warnings, nothing).

Here’s the code from our main.js file:

    var listingsArray;

    $.ajax({
        url: php_ajax_url,
        type: "POST",
        data: "action=sackville_directory_feed",
        async: false,
        success: function(results) {
            var listings = JSON.parse(results);
            listingsArray = $.map(listings, function(el) { 
              return el; 
            });
        },
        error: function() {
            console.log('Cannot retrieve data.');
        }
    });

    var directory = {};
    var directoryListings = $('.list');

    directory.renderHTML = function(z, listing){
      directoryListings.append('<div class="card card-directory col-lg-3 col-md-4 col-sm-6"><div class="directory-image" style="background-image: url(' + listing.image + ')"></div><h3 class="name">' + listing.name + '</h3><p class="description">' + listing.description + '</p><span>' + ( listing.address !== '' ? listing.address + ', ' : '') + ( listing.city_province !== '' ? listing.city_province : '') + ( listing.postal !== '' ? ', ' + listing.postal : '' ) + '</span><span>' + listing.phone + (listing.website !== '' ? ' | <a href="' + listing.website +  '">Visit Website</a>' : '') + '</span></div>');
    };

    directory.init = function(){
      directoryListings.empty();
      $.each(listingsArray, function(i, listing){
        directory.renderHTML(i, listing);
      });
    }; 

    $('.directory-filters').on('change', function(){
      var option = $(this).val();
      var label = $(this).find('option:selected').text();
      directoryListings.empty();

      if(option === 'all'){
        directory.init();
      }

      $.each(listingsArray, function(i, listing){
        if(listing.hasOwnProperty('category') && listing.category.indexOf(option) >= 0){ /* If category filter is contained within listing data */
          directory.renderHTML(i, listing);
        } else if(listing.hasOwnProperty('theme') && listing.theme.indexOf(option) >= 0){ /* If theme filter is contained within listing data */
          directory.renderHTML(i, listing);
        }
      });

      $('#current-results').html(label);
    });

    /* Get it started */
    directory.init();

    /* List JS live search */
    directory.options = {
      valueNames: [ 'name', 'description', 'category' ]
    };

    directory.directoryList = new List('directory', directory.options);

  }

It’s a WordPress site using the Sage starter theme, and that php_ajax_url bit above references the following in the functions.php:

function assets() {
    wp_enqueue_style('sage/css', Assetsasset_path('styles/main.css'), false, null);

    $ajax_url = admin_url( 'admin-ajax.php' );

    wp_enqueue_script('sage/js', Assetsasset_path('scripts/main.js'), ['jquery'], null, true);
    wp_localize_script( 'sage/js', 'php_ajax_url', $ajax_url );
    }
    add_action('wp_enqueue_scripts', __NAMESPACE__ . '\assets', 100); 

I’m new to all things Ajax, and would love some guidance about where to go next. Or, do you see anything obviously wrong?