Hello,
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 the cache of the browser, and check then. Maybe one of the additional plugins is a reason for the problem.
2/ You have custom CSS and changes in files of child theme. Please check how it works when custom code is commented / temporarily removed.
Let us know results.
Regards