Since last update, there is a problem with Woo Min/Max Plugin. When plugin ist activated and a product is published with “Group Of” Function, Cart Button will not be showed. See picture attached.
Already tried to install older Woocommerce Version. Seems not to be the problem.
Could you please check how it works with some default WordPress themes like TwentyTwenty or WooCommerce Storefront to understand is it our theme issue or not?
What I also found out: The problem only occurs if the “Full width Button” option is selected for “Product Style”. It works with the “Standard Button”. See print screens.
Please deactivate all the 3rd party plugins and activate only theme-required plugins on the site and then check the issue. I am sure your issue will be solved. Then Activate the 3rd party plugins one by one and check which plugin is creating the issue for you.
Otherwise, if the issue still exists then keep the 3rd party plugins deactivated and share the WP admin login details of your site so I will check and give you a possible solution.