When tying use the "File attachments only" feature it's disabled.
By design, if you want to "File attachments only" the original email should not be moved e.g. into deleted or filed items.
1. | Change the "After filing" option to use "Append filed date & time to subject line". |
2. | Now change the attachment option to "File attachments only" |
3. | When selecting the File… button you will be prompted to select a location for the attachments. |
4. | When finished the attachments will be filed and the subject of the original message will be updated to include the filed date & time |