Got a FIX.
It is because of Mixed Content http Urls called by KC.
this plugin will helped me fixed this.. “Really Simple SSL ”
whats is does is it converts all the http accesses even if is is used by plugins and changes to HTTPs.
it worked for me i can easily use KC builder without any hassle.
Caution: Just dont foget to take backup before adding this plugin, for a safe side.
Hope this will work for you too.
Thanks