Fixed.
wp-content/plugins/wpali-woocommerce-order-builder/public/partials/wpali-woocommerce-order-builder-public-display.php on line 332
change:
$iscolorRequired = !empty(get_post_meta( $product_id, 'wwob_available_colors_isrequired', true )) ? 'options_required="on"' : '';
To:
$wwob_available_colors_isrequired = get_post_meta( $product_id, 'wwob_available_colors_isrequired', true );
$iscolorRequired = !empty($wwob_available_colors_isrequired) ? 'options_required="on"' : '';
This will be patched in the coming version.