Loop-shaping for a MIMO system

I am studying loop shaping using the HIMAT Matlab example. More precisely, I am trying to give a 2x2 desired loop shape instead of giving Gd=8/s which is applied to both I/O couples. It seems to work correctly when I give a diagonal matrix.

However, when I try to give a desired loop shape as an anti-diagonal matrix to inverse the coupling between inputs and outputs, it gives the same results as for the diagonal desired loop shape. It seems to be because the singular values of the desired loop shape remain unchanged. Is there a way to force the loop-shaping to consider the desired loop shape as given?