Same issue here, and I found a workaround: if you disable the GPS and set date/time amd timezone to update from network, it works correctly.
Now it gets updated to the wrong timezone only when I enable the GPS. It is still pretty annoying and of course should not happen, but at least now I know when it is goning to hapoen.
ASUS, is there a date for this fix? We paid some good money to have a basic issue like this one unaddressed. Do you even realize that for most people the phone is a watch too? I dont have any other way to keep track of time during the day, it is important for us.