HPC Pack 2019 Update 3 adding IaaS node doesn't add hosts file entry

I am trying to deploy IaaS nodes that are deployed using a shared gallery image. When adding a node the IaaS VM is created successfully in Azure and the correct image is used and I can access the VM from the head node using the IP address (these nodes are not domain joined and as such don't get DNS records created).

However the head nodes (this is a clustered configuration with two head nodes) hosts file ("C:\Windows\System32\drivers\etc\hosts") is not being updated, and as such the cluster manager is throwing an error on the new IaaS Node saying 'HPC Node Manager Service unreachable'.

I can see the hosts file entries for the head nodes and the standard compute nodes, but the IaaS nodes are not created.

If I manually create the hosts file entry then the cluster manager error goes away and everything is working. I have checked through logs and I can't see any errors about failing to update hosts file and I can't see anywhere in the configuration that would allow me to force the hosts file to update.

Have I missed something in my configuration or is there a problem?