I'm on PC and this happens to me as well, for quite a while. The sim is usually getting in the yellow for hunger though and after finishing cooking the meal, will immediately pick up a plate to satisfy the hunger. It doesn't matter if you have something in queue behind it, they will still grab the plate, then put it down. If you use the "call to meal" after they have the plate, they put the plate down and then go grab another plate.
Considering free will was not enabled, and she was the selected sim - I feel she should NOT have taken a plate until I put it in her queue.
Now if I moved away from her, and free will was on, I can see why she tried to feed herself if she was in the yellow for hunger.
But even as she has the plate (free will), and then I intervene and have her do the "call to meal" she's going to consider that priority, put down the plate and then pick up another plate when she uses the call to meal action.
My workaround when two sims are in the house is I let the initial sim take the two plates. Since they've already put one down, I go to the second sim, cancel the "call to meal" action in that queue and then have them eat the first plate, my first sim put down. *sigh* it's a lot, I know.
