Proxmox 6.0 - migration issue

Just to make it worse, I am not able to remove Cloud init Device from a VM, without stoping it. So this as a workaround is pretty terrible.
 
Ok, it seems like this is a bug only in GUI. I was able to do this from console, but there is a small error.

qm migrate 191 target-node -online --with-local-disks
..........
2019-09-30 12:21:57 migration xbzrle cachesize: 268435456 transferred 0 pages 0 cachemiss 11198 overflow 0
2019-09-30 12:21:58 migration speed: 18.45 MB/s - downtime 488 ms
2019-09-30 12:21:58 migration status: completed
2019-09-30 12:22:03 ERROR: removing local copy of 'local-lvm:vm-191-cloudinit' failed - lvremove 'pve/vm-191-cloudinit' error: Logical volume pve/vm-191-cloudinit in use.
drive-virtio0: transferred: 8819638272 bytes remaining: 0 bytes total: 8819638272 bytes progression: 100.00 % busy: 0 ready: 1
all mirroring jobs are ready
drive-virtio0: Completing block job...
drive-virtio0: Completed successfully.
drive-virtio0 : finished
Logical volume "vm-191-disk-0" successfully removed
2019-09-30 12:22:09 ERROR: migration finished with problems (duration 00:02:07)

It was unable to remove this cloudinit image from a source node. I found vm-191-cloudinit image and removed it manually.