Can't get multiple sorting to work

Manvaril

I can't get the Shift+Click multiple column sorting to work. I have it server-side sorted the way I want right now but I want the user to be able to sort multiple columns

http://codepen.io/anon/pen/NRbkzN

allan

Looks like your example works for me. Li click "Main" and then shift click "Class" and it is sorted as expected.

I'm not entirely sure what the issue is?

Allan