In Windchill 11.0 and likely beyond, if you are using both a Change Notice Template and the tick box for "Propagate from Change Request", if the Change Request has attachments, then the attachments do NOT propagate to the Change Notice (even though the attributes do). If you are NOT using a Change Notice template, the attachments DO propagate.
The problem is that if you propagate and THEN apply the template, the attachments will be REMOVED. It is as if the "template" overrides the functionality to propagate attachments from the Change Request.
In practicality, this is bug that needs to be corrected or at least provided a work-around. I am listing this as a feature request per instruction from Gaurav Amrutkar re PTC TS case C14224709.