I ran into this same problem. I had the issue with tabs, and also dropdowns. It seems Kentico's jquery may interfere with bootstrap, or for some reason bootstrap does not auto-initialise tabs. So I run a piece of javascript on page load to forcibly check them. I hope this helps you.
$(document).ready(function(){
//check if design mode or edit mode
if($("body").hasClass("DesignMode") || $("body").hasClass("EditMode")){
//fix tabs
$('.nav-tabs a').click(function (e) {
e.preventDefault()
$(this).tab('show');
});
//fix dropdowns
$('.dropdown-toggle').dropdown();
}
});