Dynamic select drop down not showing

Contact form includes

<label> Document (if applicable)
[dynamicselect document id:document "wpcf7_dynamic_select_example1"]</label>

functions.php in child theme includes

function cf7_dynamic_select_do_example1($choices, $args=array()) {
    // this function returns an array of 
    // label => value pairs to be used in
    // a the select field
    $choices = array(
        '-- Make a Selection --' => '',
        'Choice 1' => 'Choice 1',
        'Choice 2' => 'Choice 2',
        'Choice 3' => 'Choice 3',
        'Choice 4' => 'Choice 4',
        'Choice 5' => 'Choice 5'
    );
    return $choices;
} // end function cf7_dynamic_select_do_example1
add_filter('wpcf7_dynamic_select_example1', 
             'cf7_dynamic_select_do_example1', 10, 2);

Label displays but no dropdown. Any ideas please.

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