Installing HAOS (Home Assistant OS) in a VM

I’m unable to create a VM in 25.04.2, and the system is saying “Can not retrieve response” (as per screenshot).

Background:
I’m currently running haos in an “Instance”, having migrated the previous Electric Eel VM zvol to an instance when Fangtooth was released. I moved the original zvol, rather than clone it (a mistake in hindsight, since I now have to remake an haos zvol - not difficult, but still…).

So: I’m now trying to recreate a ‘classic’ VM in 25.04.2 using the VM name ‘haos’, according to the guide posted above. I’ve downloaded the image, written it to my 50GB zvol, set up the zvol/CPU/RAM/networking all as per the guide.

But when I hit the final “Next” to actually create the VM, a drop down box appears saying “Virtual machine created” with a green tick - but nothing appears on the UI (again, as attached).

I’ve tried clearing the browser cache, reloaded the page AND restarted TrueNAS.

Interestingly, when I try again to recreate the vm, using the same name ‘haos’ TrueNAS says “the name “haos” is already in use”. I’ve also tried creating the vm with a range of new / different names, still no avail, but whenever I re-use the name of a vm I’ve just tried to create, the same “[name] is already in use” error is shown, so something must be saving somewhere, but nothing in the GUI.