I haven't tested it yet, but one file in the mod has changed for v1.3.9: /includes/modules/attributes.php.
There is only one added line of mod code in that file (around line 606), so it should be extremely easy to apply that to the new version - just copy/paste that line in the appropriate place in the new file.
I will get the download updated as soon as some testing for another improvement to the mod is finished.
$options_wrapper_id = 'wAttrib-' . $products_options_names->fields['products_options_id'];//gjh42