I remember I had problems in the past trying to resize or migrate instances launched using an image that was then deleted (I use kvm as hypervisor).

This is indeed confirmed e.g. here:

Now I am not able to reproduce anymore the problem, i.e.:

1- I create an image

2- I launch an instance using this image

3- I delete the image

4- I migrate the instance (nova migrate <uuid))

and this works.

Does the migration issue happen only in some particular scenarios ? 

My current setup:

- OpenStack version: Rocky

- CenOS 7.x

- qemu-kvm-ev-2.12.0-18.el7_6.5.1.x86_64 

- /var/lib/nova/instances not shared amomg compute nodes

Thanks, Massimo