Add columns to the Members List CSV Export.

my_pmpro_members_list_csv_extra_columns.php

<?php
/*
	Add data from the wp_users, wp_user_meta, or BuddyPress xProfile fields tables to the Members List CSV Export.
	
	The pmpro_members_list_csv_extra_columns passes an array of columns.
	The keys of the array are the column headings. The values are callback functions to get the value for that row.
*/

//add the column to the export
function my_pmpro_members_list_csv_extra_columns ( $columns ) {
	$columns["column_a"] = "my_pmpro_members_list_column_a";
	$columns["column_b"] = "my_pmpro_members_list_column_b";
	$columns["field_1_bp"] = "my_pmpro_members_list_field_1_bp";
	return $columns;
}
add_filter( 'pmpro_members_list_csv_extra_columns', 'my_pmpro_members_list_csv_extra_columns', 10 );

//call back to get the column a value
function my_pmpro_members_list_column_a ( $user ) {
	//this is an example to retrive user meta
	$column_a_value = get_user_meta( $user->ID, 'description', true );
	return $column_a_value;
}

//call back to get the column b value
function my_pmpro_members_list_column_b ( $user ) {
	//this is an example to retrive userdata
	$column_b_value = $user->user_url;
	return $column_b_value;
}

//call back to get the BuddyPress field ID 1 value
function my_pmpro_members_list_field_1_bp ( $user ) {
	$field_1_bp_value = bp_get_profile_field_data( array( 'field' => '1', 'user_id' => $user->ID ) );
	return $field_1_bp_value;
}

This recipe is included in the blog post on "Exporting Your Members List: Default Data and Adding New Columns" at Paid Memberships Pro here: https://www.paidmembershipspro.com/exporting-members-list-default-data-adding-new-columns/