[FIXED] [ROM] Sims dying of old age despite immortality potion

So I've been playing a witch just to familiarize myself with Realm of Magic, etc, but went back to my main family / gameplay after pretty much maxing her out (specifically to make sure she had the opportunity to craft and drink the immortality potion) I had intended to work her in/ go back to her in a bit, but when I went back, she'd already passed away of old age. I re-read description and it says it was to prevent death via old age, so? Does it only work if the sim is being actively played??? I didn't know if custom content was messing with stuff so I got rid of all of it and made a test household, no cc, got the potion of immortality, and tried again, but that sim also passed away from old age while I was in another household. Is this a bug or am I just not doing this right?

Edit: I also went in and did the whole repair the game thing prior to my second attempt, but will try again if there's a better way to do it? I just did it via Origin, I didn't get into any game files or anything like that.