Lattice not evaluating when hidden

Hey everyone this is my blender rig. I am rigging a characters spine with a variation of

So far the major difference is that I use 3 bones to deform the lattice, and instead of track to and stretch to constraints from bone to empty I use the empties as IK targets
( as recommended here )

A problem I am having (this happened with the old setup too) is that if the lattice is hidden on a separate layer it does not evaluate and deform the plane in which the empties are attached to. Is this a bug? Or is it part of a bad setup? I don’t seem to run into this problem in the tutorial’s sample files.