I run a save with aging more or less entirely disabled, so I can use specific households for when I feel like using specific pack gameplay; I have lifespan set to "long", aging disabled for all but the currently played household, and aging for all types of pets and animals disabled.
Despite this, it seems like every time I return to a household after playing with another, Cottage Living farm animals and wild animals are all set to die off immediately upon loading into the lot, irrespective of any previous differences in age (in this instance, I knew my gold chicken was much younger than the other chickens).
I realised I had also had this when I played the last login event; I loaded one of the few households I have in that save with a child, only for the child to immediate age up into a teen upon loading in. I actually think this has happened before as well.
I've found a recent bug report for similar issues, but this is marked as "fixed" (https://forums.ea.com/idea/the-sims-4-bug-reports-en/col-all-animals-aging-updying/11853294). It doesn't seem to be fixed at my end, and it's kind of ruining the point of the save.
I merged your post with the existing thread for this.
Could you please send your saves to EA as asked here: [COL] Animals aged up and died with aging off (Patch 1.116.202) | EA Forums - 12326411
