Symptom
Currently the CLI states: Setting the timezone via CLI is not supported. The clock cannot be changed after install so recommend to update this message to "Changing the timezone is not supported" or removing the clock timezone command from CLI
Workaround
This functionality has been returned in ISE 2.2 patch 17, ISE 2.4 patch 11, ISE 2.6 patch 5, and ISE 2.7 patch 1 with the note below
% On ISE distributed deployments, it is recommended all nodes be
% configured with the same time zone.
% Changing the time zone may result in undesired side effects
% Recommended to reimage the node after changing the time zone
Are you sure you want to proceed with time zone change? Y/N [N]: Y
System timezone was modified. You must restart ISE for change to take effect.