Comment 2 for bug 1570122

also, it seems like there are no address-scopes, which could be why this happens, though the subnet was created with a subnet-pool

neutron subnet-create ipv6-pd --name ipv6-pd-1 --ip_version 6 --ipv6_ra_mode slaac --ipv6_address_mode slaac --use_default_subnetpool

| subnetpool_id | prefix_delegation |