ACF Date Range

<?php
function the_date_range($args) {
  global $post;
  $default = array(
    'start_field' => 'start_date',
    'end_field' => null,
    'base_format' => 'Ymd',
    'post_id' => $post->ID,
    'separator' => '<span class="date-separator">&ndash;</span>',
    'month_format' => 'F',
    'day_format' => 'j',
    'year_format' => 'Y'
  );

  $s = array_intersect_key($args + $default, $default);

  $start = get_field($s['start_field'], $s['post_id']);
  $end = get_field($s['end_field'], $s['post_id']);

  // Checks to make sure the start is a valid field
  if($start) {
    $raw_dates['start'] = DateTime::createFromFormat( $s['base_format'], $start );
  } else {
    return;
  }

  // Adds end field if there is one
  if( $end ) {
    $raw_dates['end'] = DateTime::createFromFormat( $s['base_format'], $end );
  }

  // Sets up the $dates array
  foreach($raw_dates as $key => $value) {
    $dates[$key] = array(
      'month' =>$value->format($s['month_format']),
      'day' => $value->format($s['day_format']),
      'year' => $value->format($s['year_format'])
    );
  }

  // if the years aren't the same the whole output has to change so we check that
  // at the beginning
  if($dates['start']['year'] == $dates['end']['year']) {    
    
    // if years are the same and months are the same
    if($dates['start']['month'] == $dates['end']['month']) {
    
      // if years, months and days are the same (same date in both fields)
      if($dates['start']['day'] == $dates['end']['day']) {
        $range = $dates['start']['month']." ".$dates['start']['day'].", ".$dates['start']['year'];
    
      // if years and months are the same but not days
      } else {
        $range = $dates['start']['month']." ".$dates['start']['day'].$s['separator'].$dates['end']['day'].", ".$dates['start']['year'];
      }
    
    // if years are the same but months are not the same
    } else {
      $range = $dates['start']['month']." ".$dates['start']['day'].$s['separator'].$dates['end']['month']." ".$dates['end']['day'].", ".$dates['start']['year'];
    }

  } else {
    $range = $dates['start']['month']." ".$dates['start']['day'].", ".$dates['start']['year'].$s['separator'].$dates['end']['month']." ".$dates['end']['day'].", ".$dates['end']['year'];
  }

  echo $range;

}

@keishabien 🎉 glad you got it working!

Great work, thanks so much for doing this.