If a clone is scheduled from an instance when it is in Madrid or earlier versions, the clone cannot be canceled after the instance is upgraded to New York. The [Cancel] button does not respond after clicking on it.
Clones scheduled after upgrading to New York do not have the same issue.
Release or Environment
The issue is caused by missing information in the field 'clone_details' of the clone record. The field is introduced by New York, so it becomes empty in any clones scheduled before New York and cannot be handled by the [Cancel] button after upgrade.
Another possible reason is that the form of clone was customized previously. Please refer to KB0792637 for more detail.
Export the clone record in XML and fill in the 'clone_detail' field manually as below, then import the record so that it can be cancelled by the button.
Alternatively, you can contact Customer Support to cancel the clone for you.