Hello Leahy, Mike
Welcome to Microsoft Q&A Platform, thanks for posting your query here.
If you run the command Get-AzureStackHCI
from one of the nodes this should confirm if the cluster is registered and also within the AzureResourceUri value it will provide the subscription and the resource group they are registered to.
Additionally if you run the command Get-AzureStackHCIArcIntegration
from a powershell session logged into Azure then this will show you if the cluster is enable for Arc Integration and if the nodes are enabled.
And running command Get-AzStackHciArcSetting -ClusterName <clustername> -ResourceGroupName <resourcegroup> -SubscriptionId <subscriptionid>
will provide the name of the resource group which the nodes will be created within.
Another option is to try the registration from powershell. This document (https://learn.microsoft.com/en-us/azure-stack/hci/deploy/register-with-azure?tabs=power-shell#register-a-cluster) provides all details and also a log file is created which will help troubleshoot any issues.
Hope this helps.