Datacenter migration only works in one direction

OK I have a 3 node cluster running ceph storage and a single node with a shared ISCSI storage. Both are connected to a datacenter manager which running on a VM on the "single-node" when I select a vm "On the cluster" to migrate the "single node" all is find, however is I try to oppsite migrating a vm from "Single node" iscsi share to the "cluster" it fails with a error that says:
( found local disk 'Proxmox-synologyLUN:vm-100-disk-0' (attached)
can't migrate local disk...

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