Tax requires geolocation data to determine unless you've a tax rate that applies to "To Buyers everywhere". So it won't calculate until you're in the basket.
Will add a feature ticket to see if we can apply Tax and Promotion pricing visual changes based off geographical data in a future release for existing users with stored invoiced address already.
forge.joomlapolis.com/issues/9658
As for plan text settings they should be left as defaults. However in CBSubs > Settings > Tax you should configure seller geolocation information at minimum.