Fetching the operating point of a transistor in VerilogA with "$simprobe" always returns 0

I have the following schematic:

"VerilogA_Test" block is written so that it takes the transconductance gm of the transistor MN0 and prints its value.

The VerilogA code is the following:

`include "constants.vams"
`include "disciplines.vams"

module VerilogA_Test;

    string path = "MN0";
    real val5;
    integer count;
    analog begin
            @ (initial_step) begin
            count=0;
        end
        if( count < 5 ) begin
            val5 = $simprobe(path,"gm");
            $display("\n Value of gm in Analog context is: %f\n",val5);
        end
        count = count+1;
     end
endmodule

Whether I run a DC or a transient simulation, the output of the $display function is always:

"Value of gm in Analog context is: 0.000000".

I followed the procedure described in: $simprobe support

What am I doing wrong? I am on Spectre version 21.1.0.389.isr8

Thank you in advance!