MPA does not persist through core when loading

[shermanl]

Reported by Marta Coll:
When you draw an MPA and they you run the simulation, this works fine. But if you save this simulation and then you open it again, even if the MPA has been saved,appears in the screen, and it is applied, the running does not recognise it, so the model runs without the MPA. You have to re-draw it again every time to be recognized by the program.