Multiple Instances "Group" explode move different distances?

Hi all,
     I'm having a frustrating issue creating exploded views.
I have a fixture I've designed and I'm trying to create an exploded view showing the fasteners.

I'm moving a group of 4 identical toolbox fasteners 100mm in Y and 110mm in Z, to line up with their respective holes in the exploded view.
The problem arises when I edit the explode step and set the distance in the type-in box, the different instances of the parts are translated through different distances, even though they are all Ctrl + Selected.

This is the 4 bolts having been group-moved in +Y without any issues:

Then when I try and move them in -Z, their finished position is staggered:

Also, if somebody could explain to me how to get the explode steps to group or indend upder the "Steps" heading that would be great: I'd like to have 1 step for each part, and have the X, Y, and Z moves Indented upder each step, if this is possible.

I've managed to do it a few times by accident, but can never reproduce it when I want to!

Thanks in advance

SolidworksAssemblies