Adding a new WordPress user column is causing another column to be blank

I am currently using the ‘Recently registered’ plugin (https://wordpress.org/plugins/recently-registered/) which shows the date a customer has registered and allows me to order it.

I want to display a new phone number column but using my code now makes the Registered date column blank.

A FAQ states:

“Why is the field blank?

Because some other plugins are _doing_it_wrong(). When they created their column, they forgot to have the filter return the previous content, if it’s not their column, so it’s removing it. Since my plugin’s doing it right, I gave it a higher priority to stop that from happening in most cases.”

I am not sure how to return the previous content. My code is:

function new_contact_methods( $contactmethods ) {
    $contactmethods['billing_phone'] = 'Phone Number';
    return $contactmethods;
}
add_filter( 'user_contactmethods', 'new_contact_methods', 10, 1 );


function new_modify_user_table( $column ) {
    $column['billing_phone'] = 'Phone';
    return $column;
}
add_filter( 'manage_users_columns', 'new_modify_user_table' );

function new_modify_user_table_row( $val, $column_name, $user_id ) {
    $user = get_userdata( $user_id );
    switch ($column_name) {
        case 'billing_phone' :
            return get_the_author_meta( 'billing_phone', $user_id );
            break;
        default:
    }
    return $return;
}
add_filter( 'manage_users_custom_column', 'new_modify_user_table_row', 10, 3 );

I would be very grateful if someone can help. I use [‘billing_phone’] as part of the registration process to get the phone number.

In the ‘Recently Registered’ plugin, there are filters:

add_filter( 'manage_users_columns', array('RRHE','registerdate'));
    add_action( 'manage_users_custom_column',  array('RRHE','registerdate_columns'), 10, 3);
    add_filter( 'manage_users_sortable_columns', array('RRHE','registerdate_column_sortable') );
    add_filter( 'request', array('RRHE','registerdate_column_orderby') );

I need to make sure all data is returned.

Thank you