Race condition: softmax reads O to normalize while MMA may still be writing PV[N-1]. Single-tile wins by luck; multi-tile drifts. Move acc_cons_st construction before the wait so epilogue reuses it.
Race condition: softmax reads O to normalize while MMA may still be writing PV[N-1]. Single-tile wins by luck; multi-tile drifts. Move acc_cons_st construction before the wait so epilogue reuses it.