@carasmo thanks this confirmed my suspicion.
I wish I had seen this earlier as i opened a support thread @woocommerce
https://ww.wp.xz.cn/support/topic/cart-wont-update-1
@hide-broken-shortcodes
Its stripping the [qty] from "cart[{$cart_item_key}][qty]" if that helps at all.
I disabled all of my plugins except for the most basic ones.
https://ww.wp.xz.cn/plugins/hide-broken-shortcodes/ was causing the issue.
Its working perfectly now sorry to have bothered you.
i switched back to using the storefront theme without a child theme and the problem still occurred. so all templates are either woocommerces or storefronts.
