Hello,
Thanks for using our theme.
1/ Try to change Image Loading Type in Theme Options > Speed Optimization.
2/ Try to disable all the third-party plugins (including cache plugins), that does 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 the reason for the problem.
Regards