Reusing solution displacements - should be easy... help please!

I have a problem which should be very straightforward but I cannot get to work.
I want to solve a 3D structural mechanics frequency domain problem, and reuse the velocity of particular surfaces in another study (of the same geometry). Whilst the structural mechanics solves ok, and I am happy with the results, I am experiencing difficulties in reusing the solution data. I have tried every combination of initial conditions, general extrusions, prescribed displacements etc etc I can think of, but cannot get it to work.

So... I have taken it right back to basics (a single plate, with a stationary load), but am no further on. Here's a simple example: if I apply a point force to a plate, I can see the resulting deformation fine. If I then create a new study, disable the force, and use the previous solution as the initial conditions, I do not see the same result. Why not? And how else can I use the displacement on a particular surface in another study?

I could not find much inspiration in the documentation or tutorial models for this, I feel like I am missing something fundamental here. I have spent days now going round in circles, so any tips/advice would be very gratefully received! Thanks!