@_Annika_, like Stormi71 said, I have also only seen this with meals, but it is happening quite often when my sims make meals. I would say that about 50% of the time, they stop cooking halfway through.
Like you said, there's no such thing as a "half-made" drink, so I don't think I would really notice if the same were happening with drink making. Usually I queue up a bunch of drinks for one sim to make and then go focus on another sim.
There is one drink-making achievement that is always hard for me to achieve during parties: "Make 10 drinks during a single social event." It is part of achieving the Mixologist Aspiration,. I queue up about 7 drinks, as allowed, but when I go back to check on that sim, they are often far behind on their progress. So, it would be reasonable to assume that the same thing could be happening in my game as in yours, but I can't say for sure.