Hi there!
I have checked the issue and noticed a JavaScript error that is causing this problem.
Just to verify, are you using any WPO Minify plugin or variation plugins? If yes, could you please try deactivating the variation plugin and the minify plugin to see if that resolves the issue?
Also, if you still face the same issue, I’d like to understand your site properly. Please share with us the necessary information below for us to investigate the issue further:
- System Status Report?which you can find via WooCommerce > Status
- Fatal error logs?(if any) under WooCommerce > Status > Logs.
Please use https://pastebin.com/ or https://gist.github.com/ and share a link to that paste in reply here. Once we have more information, we’ll be able to assist you further.