flip-flop issue in Capture

Hi all

I'm running simulation which involves a flip-flop. Problem is the output of the flipflop stays low in this particuliar circuit no matter the input is. I checked the setting for CLR and CLK in datasheet and the flipflop works fine in any other circuits but this one. I did initialize it with 0 by set DIGINITSTATE to 0. Did I do it wrong or it's a bug? How do I solve it if possible?

I tried 7474 and 74175 and such but none of them work in this circuit

I find post with same problem. Now I start to think of it a bug o.O