Programatically re-order images in the ACF gallery add-on. Orderby Title, ID, etc

You can use Php’s usort() function with a callback. For example, if you want to sort images by ID, you could try something like this (stealing the filter that @Milo used in their answer):

<?php
function sort_callback($a,$b)
{
  if ($a['id'] == $b['id']) {
    return 0;
  }
  return ($a['id'] < $b['id']) ? -1 : 1;
}

function my_acf_load_field( $field ){
  usort( $field, 'sort_callback');
  return $field;
}
add_filter( 'acf_load_field-gallery', 'my_acf_load_field' );

You can adjust the sort_callback function to sort by whichever value in the $image array that you’d like.