Hey @AmandaCH . Sorry to hear you are facing this issue.
I just tested the registration and it worked on the fly.
Could you try to register with the CLI?
Register for the preview:
az feature register --namespace Microsoft.Storage --name ContainerSoftDelete
az provider register --namespace 'Microsoft.Storage'
Check the status of your registration:
az feature show --namespace Microsoft.Storage --name ContainerSoftDelete
Please let me know if you still are not able to register the feature.
PS: I am going to search if we have any specific ETA for the registration.