Add nickname to the Member Profile Edit frontend page.

add_nickname_pmprorh_user_table_fields.php

<?php
/**
 * Add nickname to the Member Profile Edit frontend page.
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 *
 */
function add_nickname_pmprorh_user_table_fields( $user_table_fields ) {
	
	// Set the return value to an array if it is not one.
	if ( ! is_array( $user_table_fields ) ) {
		$user_table_fields = array();
	}

	// Add nicename as a new field.
	$user_table_fields[] = 'user_nicename';

	return $user_table_fields;	
}
add_filter( 'pmprorh_user_table_fields', 'add_nickname_pmprorh_user_table_fields' );