Apple Mail 16.0 rule-based forwarding doesn't include attachments - workaround

We needed to get mail addressed to an iCloud alias also delivered to a different iCloud user for a long-running project. We created a new rule with the "Forward Message" action and the iCloud email address of the desired user to do this automatically. The intended iCloud user received messages as expected, but attachments did not accompany the delivered messages. Manual forwarding of the same messages worked with any Menu >Edit > Include Attachment With Replies options for which attachments would normally be sent. The result of these tests indicates different behavior between manual and rule-based forwarding.

(Note that our testing involved small PDF image files of under 100 kB.)

For us, changing the rule action to "Redirect Message" solved this particular problem, but it might not provide the desired behavior for all use cases.