Usually the dropdown list opens up above other elements that come after the dropdown. If you have two dropdown elements arranged vertically, the list of the first dropdown element opens up below the second dropdown element.
I tried working with z-index, making the the dropdown and/or dropdown-toggle lower level than the dropdown-list, but it doesn’t work out.
Remove all the z-index properties you’ve set (click on the blue label z-index then remove). So for your dd element and your dropdown. It’s messy because your dd is shared at 1 and the manu at 10 is the child of the dd at 1.
Give a unique class to each of your ROWS, then position:relative then z-index 2 for the upper row, 1 for the lower row. Now it should work.