FYI, I may have found the root cause of the issue...
Your JS script:
plugins\system\t3\base-bs3\js\frontend-edit.js
is removing btn-group as a class, for radio buttons:
$('fieldset.radio').filter(function(){
return $(this).find('input').length == 2 && $(this).find('input').filter(function(){
return $.inArray(this.value + '', ['0', '1']) !== -1;
}).length == 2;
}).addClass('t3onoff').removeClass('btn-group');
