Please try to disable all the third-party plugins (including cache plugins), that does not come bundled with XStore https://xstore.helpscoutdocs.com/article/36-included-plugins , clear the cache of the browser, and check then. Maybe one of the additional plugins is the reason for the problem.
Please check how emails work when XStore > Built-in Email Builder is disabled.
Check how it works with the default theme – Storefront activated.
Let us know the results.
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.