You might have an issue in your circuit. I believe the first X gate on line qB1 should actually be on line qB0 to be symmetric with the upper block.

You might have an issue in your circuit. I believe the first X gate on line qB1 should actually be on line qB0 to be symmetric with the upper block.

Maybe you can also try to move those X gates just before the two controlled gates as they act on the first and third qubit you measure but not on the second and fourth ones (in descending order).