As @TheDeadMedic mentioned the API will exclude any meta with underscore. It’s not a good idea to remove the underscore as it might break something in your code or dependencies, however you can try adding a code like this in your functions.php to unprotect the desired meta
add_filter( 'is_protected_meta', 'wp692_meta_unprotect', 10, 2 );
function wp692_meta_unprotect( $protected, $meta_key ) {
return $meta_key == '_company_phone' ? false : $protected;
}