I have checked your issue and found the issue appears. The thing is on your site there are 61 plugins activated. There is a possibility that a third-party plugin conflicts with the AMP plugin and causes the issue. Please 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 the reason for the problem.
And if the issue will still persists then please remain all the third-party plugins deactivated on your site, and allow permission to debug your site which includes deactivating all the third-party plugins and on-site Customization as well. So that I will check and assist you accordingly.
Note: Please take the complete backup of your site first.
Regards 8Themes Team.