Please make sure you have added membership plans from admin. If you are still facing the issue, it seems like there is some plugin/theme conflict. Just to be sure, disable all the plugins except WooCommerce and WCMp and check again.
Hi,
We tried to recreate this on your site but didn’t face any such issues.
Here is the link-https://www.awesomescreenshot.com/video/6325254?key=41880f955ffac13fdb8a920d7b24132f