Default option text in dynamic dropdown

We have the code below in the functions.php file for dynamic dropdowns in several forms. It worked fine until recently, perhaps since the last WP update. The debug messages indicate the function is both called and executed, but the default text is not displayed in the form.

Can you confirm this is a new bug, or is there something we need to modify in our code?

Doris

function workshop_title_dynamic_default_option($default, $name, $cf7_key){
    error_log('DEBUG: workshop_title_dynamic_default_option called!');
    if('member-led-workshop-registration'!==$cf7_key || 'workshop-title' !== $name){
      return $default;
  }
  $default = 'Please select an option...';
  error_log('DEBUG: workshop_title_dynamic_default_option executed!');
  return $default;
}

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