When creating a new Event Notification in the system, you can't find the Attachments option under Subscription section.
SAP Cloud for Customer
Reproducing the Issue
1. Go to Administrator work center.
2. Open the General Settings.
3. Go to System Administration then Event Notification.
4. Go to All Consumers and click Add.
5. Create it.
6. Go to Subscriptions section then click Add.
7. You don't have the Attachments option under Business Object field.
Currently changes on attachments are not supported as event using Event Notification feature.
This is the system expected behavior.
Event, Notification, Attachments, Missing , KBA , LOD-CRM-CMN-EVT , C4C: Event Notifications , How To