Incus - Setting migration.stateful for stateful snapshots

I'm trying to get to grips with [Incus](https://linuxcontainers.org/incus/introduction/) , because it looks like it is a fork of Canonical's LXD, which I can run fairly easily on Debian 12 with a deb package, rather than using snaps. I have it all set up in a virtual machine on my KVM, running with both a basic directory based storage pool, and a zfs storage pool. I have spun up a test container called test that I want to take a stateful snapshot of, but it tells me that: > To create a stateful snapshot, the instance needs the migration.stateful config set to true After reading [the documentation on configuring an instance's options](https://linuxcontainers.org/incus/docs/main/howto/instances_configure/#configure-instance-options) , I have tried running these various commands (the first being the one that I think is the most likely to be correct):

incus config set test migration.stateful=true
incus config set test config.migration.stateful=true
incus config set test.migration.stateful=true
incus config set migration.stateful=true

... but I always get an error message similar to below about an unknown configuration key: > Error: Invalid config: Unknown configuration key: migration.stateful I have also tried setting the option through the YAML configuration as shown below: ... but it just gets stuck on "Processing..." How is one supposed to enable stateful snapshots of incus linux containers? Perhaps this is just not possible because I am running inside a virtual machine, rather than the physical box?