I can’t see Theme Custom CSS area in Theme Options. Please check. Have you disable it using additional customization or a plugin?
Try to disable all the third-party plugins (including cache plugins), that do not come bundled with XStore https://xstore.helpscoutdocs.com/article/36-included-plugins , clear cache of browser, and check then. Maybe one of the additional plugins is a reason for the problem.
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.