This issue needs is causing me to loose a lot of sales and needs to be fixed ASAP. With most of my products, when the page loads the varient selector is automatically messed up and no matter what varient you choose to add to cart it always shows the defualt variant in the cart. Sometimes it functions normally but most of the time it does not. I would really like this to get fixed!
Did it work before you've added the Social Proof App? Highly likely it a side effect of this App.
If not much configured in the App, I'd try to remove it and see what happens. Should be enough to just delete it.
Otherwise more thorough check is needed -- probably there are other ways to solve it
Looks like the usual conflict of loading too many copies of jQuery library. Your theme is loading it's own copy, ver 3.1.1 (probably somewhere at the bottom of the theme.liquid Layout). But some apps get loaded before this, look for jQuery, find none and load it's own copy.
Try to move the line which loads jQuery higher, like to the <head>
Is it possible that you are using specific apps that are causing conflict with variants?
We have seen this problem in many client stores, please update us on this or contact us if you need any assistance.
We will be happy to help.