I have noticed this problem since the most recent patch (released on 11/11/19 I believe). My Sims will make food anywhere but the kitchen really.
I have seen this problem in most of my households, in all my saves and it happens nearly every time I ask a Sim to cook.
One of my households has three different trailers on one lot (sort of like a mini-trailer park) and the Sims always run to another trailer's kitchen to use the counter, even though they have a perfectly good counter in their own trailer.
Another instance that I have seen in my game is sims walking to different levels to prepare food. For example I have another household with only two sims. They have a large kitchen with tons of counter space and yet they still walk downstairs to the basement to prepare food in the laundry room. Once it's prepared they then walk back up to the kitchen to either set it down (if food is ready) or to use the stove to finish the meal.
The counters in the kitchen do have some appliances on them (Tea brewer, coffee machine and microwave, as well as a dishwasher under the counter) as well as some decorative objects (mug rack, sunflowers in a vase from painter career, paper towel roll), but the majority of the countertop is free for use.
I play on a MacBook Pro and I have Seasons, Parenthood, Laundry Day and the Holiday Stuff pack installed, no Mods or CC, and the game is up to date with all patches.
