Problem running Update-ClusterFunctionalLevel on Server 2019

Hi

I have in-place upgrade a 2 node SQL cluster (from Server 2016 Std. to Server 2019 Std.). The whole process worked as expected.

Now I want to run Update-ClusterFunctionalLevel, but it is returning the following error:

Update-ClusterFunctionalLevel : You do not have administrative privileges on the cluster. Contact your network administ
rator to request access.
    Access is denied
At line:1 char:1+ Update-ClusterFunctionalLevel+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+ CategoryInfo          : AuthenticationError: (:) [Update-ClusterFunctionalLevel], ClusterCmdletException+ FullyQualifiedErrorId : ClusterAccessDenied,Microsoft.FailoverClusters.PowerShell.UpdateClusterFunctionalLevelCo
   mmand

I the Microsoft-Windows-FailoverClustering/Diagnostic eventlog it gives me the following error:

EventID: 2051

Description: [CORE] mscs::ClusterCore::VersionUpgradePhaseTwo: (5)' because of 'Gum handler completed as failed'

I think all permissions are correct, but I can't find the root cause, can you please help me?