Please see the code below (very stripped back and not my full function). I've also got a fiddle that you can test it at: https://jsfiddle.net/glenn2223/uk7e7rwe/1/
var 
    hov = $("<div class=\"over\">I'm Over You</div>"),
    box = $("<div>Result: WAITING</div>")
$("body").append(hov).append(box);
$("#MeHover").on('mouseleave', function(){
    var d = new Date();
    box.text("Result: " + hov.is(":hover").toString().toUpperCase() );
});
We have a div and div.over overlaps it slightly. When you move from div to div.over I want the function to return true. 
In my full function: this stops it from hiding the div.over element.
Opening it in Chrome it works as expected. However, it's not in pretty much everything else (Tested in: Edge, IE11 and Firefox).