Hi @bshaughnessy
Could you please try to use the update_field() function instead? You should be able to do it like this:
// Please use field key instead of field name
$field_key = 'field_123456789abc';
// Get the field value first if it's available
$repeater_value = get_field('repeater_field_name');
// Add the row to the repeater
$repeater_value[] = array('memos_upload_file' => $attach_id);
// Update the repeater field
update_field($field_key, $repeater_value, $post_id );
I hope this helps 🙂
