Hi,
Addresses are normally only unpublished when you try to edit it while it's already been used for one or several previous orders.
In that case, the address stored in the database is unpublished so that you don't see it for the customers (but still there for the previous orders) and the modified address is stored published so that you can see it.
So normally, you don't have to see the publish/unpublish state of addresses as it is managed internally.
I'm not sure what you mean by "I have a clean install" ? Normally, if you install a HikaShop 4.2.1 on a Joomla where you didn't had HikaShop installed before (which is what I would describe as clean I suppose), the default popup mode is "Vex". And it has been so for a while now. The fact that you had it set to "bootstrap" means that you had an older HikaShop installed before at some point on the website.
Which then leads me to ask you to check if you don't have mass action configured on the "address" data type in the menu System>Mass actions (as they could forcefully unpublish the addresses when being created), or some address plugin which could also unpublish the created address for some reason.
Also, check if you have the folder administrator/templates/isis/html/com_hikashop/user/ via FTP and if you do, try renaming it.