I'm using default CT store template and Shipping by Location Weight Threshold w/Options shipping plugin (https://github.com/CartThrob/cartthrob-shipping-by_location_weight_threshold_w_options) on EE 2.9/CT 2.6, and running into issue on Shipping template where toggling between countries doesn't correctly reset the shipping options select display.
It does generate the correct shipping price for the leftnav display, but the select itself doesn't refresh to show the proper rates. So, if you switch from USA to UK (or any other country), it'll change the leftnav from USA to correct UK shipping amount, but the select still shows the USA options.