Update method doesn't have any effect?

I have set of selects country, zip/postcode, state & city that are linked so when one is selected say state it'll only show cities within the standard select that are within that state, works perfectly with the normal selects.

However after applying niceselect the list isn't being updated with the original selects options, I've tried using:

jQuery('select').niceSelect('update');

But it doesn't seem to have any effect, I can see in the source the original selects are updating properly its just the replaced select list isn't, am I using this correctly? Do I need to call it with something else? Any help is greatly appreciated!