Bug in checkout page

Hi!
Congratulations for the plugin, very helpful.
Woocommerce Smart Code is the only plugin that permits to specify COD extra fee based on different shipping methods of the same tipology (for example similar Flat rate).

It’s all ok but if I try to modify the shipping method in the checkout page (so the page updates automatically) the fee should be modified but the plugin seems to work casually.

I Have created two Flat rate shipping methods with two different courier services. When the first is selected COD fee will be 4,00 eur, when the second is selected the COD fee will be 10,00 eur.
In checkout page obviously is still possibile modify the shipping method but the fee not always change.

Thanks in advance!
Paolo