Hi,
There is no javascript error and the problem appears only in Chrome.
Now I found a similar problem when modifying the status of the order ( also only in Chrome ).
Could be something in my Chrome, but as far as I know there are no changes in it's settings.
I've ended up modifying the file :
joomla_root/media/com_hikashop/js/hikashop.js
I've added some lines of code in the function xRequest ( after the line 163 ):
var dRand = new Date();
var nRand = dAlex.getTime();
url = url+'&'+nRand+'=1';
This was the ajax call is never cached.
In case you find this helpful maybe you will modify the code in the next version of Hikashop so I don't have to do it after each update.
I suggest a similar approach on all ajax calls.