IE crossing out pseudo element CSS?

I had this exact same issue! You must give your :before and :after pseudo elements a display property.

Add the following to the :before and :after.

display: block; 

This should fix your issue. :)

To add onto the answer above. I tried display: block but my issue was that the background image was coming out warped. Instead I used below:

display: inline-block;

This fixed my issue with warped images within my :before :after

This is a known issue, but the styles are in fact being applied. The developer tools thinks the pseudo-element styles are being overridden by the parent-elements corresponding styles. This is easily demonstrated by inspecting the Computed style of the parent-element and looking at (what the F12 tools believe to be) competing styles:

Again, however, these styles are in fact being applied to the correct elements - regardless what the developer tools believe or suggest. You can confirm this by running over the parent-element and the two pseudo-elements and logging their computed height:

(function () {

    var el = document.querySelector( ".newbutton" );

    [ "", "::before", "::after" ].forEach(function ( e ) {
        // Output: 74px, 80px, 80px
        console.log( window.getComputedStyle( el, e ).height );
    });

}());

I'll check to see if we already have an internal issue tracking this bug, and add this question to it. Generally speaking, we try to give issues like this the amount of attention proportional to the amount of grief the issue is causing in the real world. So having your question as a new addition on the ticket may help us move a fix forward :)