Hello,
Check how it works when a default theme, like Storefront, is activated on your site.
If this is independent of the theme:
1/ 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.
2/ Contact your hosting provider and ask about assistance
Regards