In reply to shivamdec:
property gray_cnt_value_chk;
@(posedge clk ) (start_addr == 'h10 && iso_input) |->
##1 ($stable(gray_count) || gray_count === "X")[*1:$] throughout (iso_input[->1]);
endproperty
You’re checking a sequence throughout another sequence
Ben systemverilog.us