Hi guys , I am using Alidropship on woo, I had similar issue after installing the rocket caching plugin on woocommerce. However nowadays Rocket provides a setting to deal with it. On rocket settings you may go to Advance Rules / Never Catch Cookies and add the cookie ID like this : current_cu and voila !
This solution was described by me in different thread a year ago..
Is still not recommended.. because for your first time visitor is still gonna have flag cache issue for the first load.(you first time visitor is going to see the flag of the previous selection you have load your site first time , the currency is going to change but not the flag)
After the second load 99% is going to work ok.
So the best solution is to use dynamic cache but your server must allow it . … like for example interserver is a litespeed cache server.. you can use the alidropship currency switcher without any issue if you follow some more steps..
Anyway i never use the alidropship currency switcher as is not allowed the customers to checkout in preference currency (only the store default currency)
I have replace it with Alias currency switcher.
They alidropship team promise is going to fix they issue of the currency switcher but is never happen for years now.