I used AC36 Load Missiles this turn. As it was a Move and Do, I assumed (be it ever so dreaded) that if I was already at the planet location I needed to be to load missile I could leave the LOCATION #1 slot blank.
Fleet 120 reports destination coordinate is not valid
Assumption bit me in the posterior again...
So I assume (be it ever so dreaded) that for AC36 Load Missile, one has to put the planet location of where you will be loading missiles, even if you are already there.