Flexible Sync "Bootstrap the Realm with Initial Subscriptions" not working in Swift SDK

In the SwiftSDK the “Bootstrap the Realm with Initial Subscriptions” does not seem to work; no initial subscriptions are being added. Implemented according to the docs.

this should work but does not add a subscription:

let flexSyncConfig = user.flexibleSyncConfiguration(initialSubscriptions: { subs in
                    subs.append(
                        QuerySubscription<Example>(name: "example") {
                            $0.exampleId == user.id
                        }
                    )
              })
            do {
                let realm = try Realm(configuration: flexSyncConfig)
                self.realm = realm
            } catch {
                print(error.localizedDescription)
            }

this works:

if let user = app.currentUser {
            let flexSyncConfig = user.flexibleSyncConfiguration()
            do {
                let realm = try Realm(configuration: flexSyncConfig)
                let subscriptions = realm.subscriptions
                subscriptions.update {
                    subscriptions.append(
                        QuerySubscription<Example> {
                            $0.exampleId == user.id
                            })
                }
                self.realm = realm
            } catch {
                print("error: \(error)")
            }
        }