Per Engineering unlike PIM SM, in PIM DM mcache entry would be created based on the incoming IIF. However no OIFs would be added if the group is in multicast boundary. This is because of the difference how the protocol is working. PIM DM needs prune to be sent upstream which is based on 0 OIFs in the mcache entry. Hence the difference in SM and DM. This has been verified in lab with receivers and traffic not forwarded with multicast boundary applied on the group.