$monitor is not printing the all value changes when class variable is used inside the system task

In reply to Naven8:

I tried with $display. It is working. But if i give some delay in repeat block like below, then the all the random values should be printed. But the output is same.
Can i know the reason? How can i print all the random values using $monitor in my scenario?
In this case how a time stamp can be defined?

initial begin
repeat(10)
#10;
s1=new;
s1.randomize();
end