How to retrieve ID from KeyVault addon profile with ManagedCluster(AKS) C# Pulumi

Question

I'm creating a managed cluster with a keyvault in Pulumi C# and struggling to retrieve the clientID from the ManagedCluster AddonProfile.

Here's my AddonProfile creation:

AddonProfiles =
        {
            { "azureKeyvaultSecretsProvider", new Pulumi.AzureNative.ContainerService.V20220902Preview.Inputs.ManagedClusterAddonProfileArgs
            {
                Config =
                {
                    { "enableSecretRotation", "true" },
                },
                Enabled = true,
            } },
        },

Originally I had

AzureKVObjectId = cluster.AddonProfiles
                         .Apply(x => x["azureKeyvaultSecretsProvider"].Identity.ClientId);

which worked but has since stopped working with a NullReferenceException.

Any idea on the correct way to retrieve the ObjectID of the identity that this creates?

Thanks!