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. Let us know the result.
If the problem is independent of plugins, provide temporary wp-admin and FTP access, so we can take a closer look.
