This is a strange one.
I've been using J2Store/J2Commerce for years - a paid "Pro" user before Pro was released as free.
I have always found setting up localisation as a weak spot on J2Store, with it being a real pain if you only want a one or two countries enabled for shipping.
Recently, I have tried a dozen ways to set up a new shop with shipping within Ireland and UK but no matter what I do, the front end will not allow selecting of the zone within the country and therefore cannot complete shipping. It just shows "Select" on the Zone / Region dropdown, even after country is selected, and even with only zones in one country enabled in Localisation settings.
Have I missed something or is there a bug tripping me up here?