It's not the lot challenge, because I haven't even used that at all and noticed that hot pots are broken. I'd have them make a hot pot to share with others and then somehow nobody could seem to start eating.
Have encountered so many similar bugs in the past, like with high chairs and starving toddlers, that I just gave up using a hot pot. It wasn't like this, then suddenly it was, so I figure an update broke the hotpot function somehow. But who knows. I haven't played sims4 in a good while but reading this, had to agree, seems like something made hotpots buggy when they weren't before.