Simple Deform on my Lattice doesn't work as expected

Hello! I have followed this tutorial using 2.81 and everything worked fine until I tried a different type of shield.

I've made a circular one using only a quarter of a circle made with 8 verts. It has 3 modifyers NON applied: 1st Mirror on X, Y Axis; 2nd Subdivision Surface and 3rd Lattice.

The problem is with the Lattice object. I wanted to build a rounded shield using two Simple Deform modifyers. One curving de Z and the other the X.

I can't place a Second Simple Deform without messing the Shield. Locking the Y axis on the 2nd Simple Deform only makes it worse.

Could anyone help me? What am I doing wrong?

Thanks in advance! :-)