Slider cart won't update with new upsell app

[Dharma91]

I noticed my slider cart won't update when I click my upsell checkbox on my product page. I already contacted the slider cart developers and the upsell developers. They both kept blaming each other and telling me that it was the other app's fault but then they suggested I get a developer.

As you can see in the screenshots, the earrings won't appear in the cart unless I refresh the page. Can anyone help me? I am using a modified version of dawn theme.

https://lavajewels.com/products/wife11lk