CognitoUserSession is not valid because idToken is null - android-studio

Question

I'm developing an app in Android Studio using amplify.
I need that unauthenticated users be able to read a type but need to signed in to create or modify it.
To achieve that I did the following:
I configured my auth to allow unauthenticated logins, following the steps in this documentation https://docs.amplify.aws/lib/auth/guest_access/q/platform/android
I configured my graphQL Api with Amazon cognito user pool as the default authorization type and IAM as additional authorization.
defined my type in schema.graphql this way
type Property #model\
#auth (
rules: [
{ allow: owner, operations: [create, update, delete, read]}
{ allow: private, operations: [create, read] }
{ allow: public, operations: [read], provider: iam }
]
)
#key(name: "propertiesByPrice" fields: ["modelType", "price"] queryField: "propertiesByPrice")
#key(name: "propertiesByLot" fields: ["modelType", "lot"] queryField: "propertiesByLot")
{
id: ID!,
imageUrl: String,
offerType: OfferType,
price: Int,
type: PropertyType,
rooms: Int,
bathrooms: Int,
parkingSpace: Int,
lot: Int,
state: String,
city: String,
neighborhood: String,
street: String,
number: String,
zipCode: String
modelType: String
}
So the guest users will be able to read the type Property but need to be signed in to create one and need to be the owner to modify it.
For tests I'm making the following query
Amplify.API.query(ModelQuery.list(Property::class.java),
{ result ->
Log.i(TAG, "listProperties: succeeded $result")
},
{ exception ->
Log.e(TAG, "listProperties: failed $exception")
})
I get the right response with signed in users but when I try to run it as guest i get the following error
W/CognitoUserSession: CognitoUserSession is not valid because idToken is null.
W/AWSMobileClient: signalTokensNotAvailable
Is there anything else I need to configure? Thanks in advance