`cluster.superuserSecret` fails to get the value from k8s secret encrypted with sops

I have the `kind: Secret` which is then `helm secrets encrypt` and referenced in the customized chart `values.yml`:
```
cluster:
instances: 3
imagePullPolicy: IfNotPresent
superuserSecret:
name: superuser-secret
enableSuperuserAccess: true
```
However, installing the chart hits the following error:
```
STDERR:
coalesce.go:306: warning: destination for cluster.cluster.superuserSecret is a table. Ignoring non-table value ()
Error: values don't meet the specifications of the schema(s) in the following chart(s):
cluster:
- at '/cluster/superuserSecret': got object, want string
```