Hi Dan,

I am thinking your position: relative is incorrect and I say that because left and right functions naturally work better with position: absolute; My suggestion would be to change it to that below and see how that works for you. You can override it in project settings in the CSS/LESS area to test it out...

.blockslider-article .blockslider-control-right {

    position:absolute;

    top:200px;

    left: 48%;

}