Old version was working just fine. Updated last weekend and now variable products cannot be placed into the cart because no "Add to Cart" button appears.
I'm losing orders and money. Can't talk to tech support. All week tech support has been unable to log in to my WordPress login. Their advice on how to fix did not work. I'm frustrated and my boss is recommending we switch back over to a more expensive hosted cart like BigCommerce, which has its own problems.
Advice from FatMan49 above is very good. Wait at least a month after new updates become available to allow them to work out all the bugs.