Unable to execute “set netflow-sampler” on interface with HA (ha-direct enabled) on FortiGate-200G

We are currently using two FortiGate-200G units in an HA configuration with the ha-direct feature enabled.
After applying the following NetFlow configuration, we were unable to execute the set netflow-sampler command on the target interface.
If there is any way to achieve this, we would greatly appreciate your advice.

NetFlow Configuration
config system netflow
    config collectors
        edit 1
            set collector-ip "x.x.x.x"
            set collector-port 9996
        next
    end
end

Attempted Command on the Target Interface
fw # config system interface 
fw (interface) # edit port1
fw (port1) # set netflow-sampler both

command parse error before 'netflow-sampler'
Command fail. Return code -61