To further the suggestion Cecil Smalley provided, you can review the following sample which demonstrates the sorting behavior working as expected:
http://jsfiddle.net/558gtjxs/2/

Hope reviewing a working sample will help you solve this in your application.

Trying this post again.  I can't exclude a column from sorting in my igGrid:

No Matter where I put this:

columnSettings: [ {columnKey: 'Name', allowSorting: false} 

Name is still subject to sorting.

This doesn't work either (Name still sorts):

key: "Name", headerText: "Name", width: "4.5%", dataType: "string", allowSorting: false,

Here's the code I use for igHierarchal level I want to sort, 

but everything sorts and I'd like to exclude certain columns:

features: [
{
name: "Sorting",
type: "local",

},

],

Help!  :)