I am having similar issue.
Adding too many into cart hides the buttons and pushes them down and down.
IF I resize my browser, issue goes away; reloading the page works but just closing and reopening the Cart doesn’t make any difference.
I’ve Noticed this issue happens on Firefox and Safari (tested on Mac OS).
On Chrome Browser, cart seems to refresh and shows the buttons if you wait a while without resizing.
On Mobile Browsers (including Chrome), since we can’t resize the browser, reloading is always required.
I’ve tried add_action() code above and this causes cart to not function; cart does not open at all while cart icon is displayed only. Nothing happens when cart is clicked.
Using WordPress 4.9.8 & WooCommerce 2.5.2.
Any help would be appreciated as I am evaluating this plugin to integrate to our website.