Windows Phone 8.1 : ToggleSwitch isn't working as expected -

i have windows phone 8.1 application being developed past 1 year.

here's how toggleswitch used in code

<toggleswitch ison="{binding issplit, mode=twoway}"               isenabled="true"               foreground="{staticresource primarycolor3brush}"               offcontent="off"               oncontent="on"/> 

toggleswitch used in few pages. behavior of toggleswitch buggy. toggleswitch not detect either "drag" event or "click" event when done on vertical slider of switch. following image shows arrow pointed part of switch click or drag doesn't defected.

this problem on every toggleswitch in application. when create fresh windows phone 8.1 project , add toggleswitch, works smooth expected. way able isolate problem happening on our current project.

so debug this, tried following

1. i saw if had default styles being applied toggleswitches in our app in general modified original behavior - no there none
   2. i created fresh new page in current app created toggleswitch within grid - no luck, toggleswitch still buggy.
   3. i used blend edit copy of default template of toggleswitch, pasted same onto toggleswitch on page - still, behavior didn't fixed.
   4. i tried see if of ancestor classes of toggleswitch had been applied default different style - no, there none.

i've spent hours on i'm not sure causing toggleswitch act buggy. highly appreciate if has idea of happening or if share few other things try might fix.

thanks in advance.