I noticed that you cannot change the notification hub in the UI. There is a simple workaround (it will be fixed by the way).
Here is a picture of what I mean:
Run this powershell script from the Azure Powershell (or do similar using the Azure CLI):
Remove-AzureRmResource -ResourceId /subscriptions/<SUBCRIPTION_ID>/resourcegroups/<RESOURCE_GROUP>/providers
And I get my wizard back!
Let me know if this is helpful by dropping me a note!