Woocommerce – buy button should be hidden until variable selected – its always showing though

On the frontend of my website, when viewing a variable product, the user is presented with a dropdown box to select a variation option. Selecting an option should then reveal price and Add to Cart button for that variation, but for some reason the buy it now button is always showing – where as it was hidden until the customer selected a variable. I re-installed membership pro last month and dont know if it caused a conflict?? I have deleted it MP but the problem is still there. I dont want to publicly display my sites url, its HA site and I have granted support access.