I created a staging site but Jetpack wouldn’t allow me to ‘authorise’ when trying to ‘set up Jetpack’.
I have been through and disabled each of the other plugins active on our site and it didn’t make a difference. The scroll defect was still there.
Once the Jetpack plugin is disabled the site still needs to be restored from backup.
I tried it a second time and had exactly the same issue.
I saw exactly the same problem using a different browser and device.
I haven’t gone through the process of disabling the other plugins so I can try that but I don’t think we’ll be testing a different theme.
When you ask for the address of the jetpack site I’m not 100% sure what you mean but our company site is http://www.bangpostproduction.com. The Jetpack plugin is disabled currently and the backup restored so you won’t see the same issue.