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.
Why you do not want to provide temporary wp-admin access? To be able to talk about refund, we need at least confirm the error.
We would like to solve the situation in the best way, and fix the problem.
