Slider getting stuck in the middle

I have created a Storyline 3 eLearning with a six-point slider, correlating to six layers of content (with sound). When you move the slider to the right, point 1 works great. Point 2 works great. Point 3 works great - but then it won't move past that. I've attached this particular slide for reference. Any suggestions as to how to fix it would be very appreciated!