We had this problem too... turns out to be an unrelieable array.prototype.sort() algorithm in the IE8 JavaScript runtime. Kendo.web.js reuses the a and b parameters in it's sort compareFunc - which IE8 does NOT like and "sometimes" returns an undefined.
See https://www.zachleat.com/web/array-sort/ for more information and a life demo.
I had to patch kendo.web.js to get rid of this "error". It is still existant in Kendo version 2016.3.914, btw.!
Quote from the Leatherman site: "Internet Explorer can’t make you do anything, it can only make you wish you hadn’t."