I have this same issue going on in my game. I found a workaround (until EA fixes it. This is not saying we should resort to having to do this for all time. It still needs fixed. This is just a way to get relief until EA actual fixes the issue). I posted on the Sims forums and I'll copy and paste my post from there, here:
WORKAROUND:
Okay, I've done some testing (about a sim day - now it's been 3 sim days, and the issue is gone for me) and I think I've figured out how to stop YA and older sims from queuing up to do dishes. I'm sure it would work on Teen and younger as well, but you will be losing your manners, so I prefer to do it after they've aged up. I tested this with a sim that did not get the high manners trait as a YA (she had high manners, just not high enough for the trait). So be warned, you might lose that trait, I have no idea as I don't have anyone with the high manners trait to test. But, if it's driving you crazy to have a sim constantly trying to wash dishes, this may work for you....
Turn on testingcheats on
put in cheat window: stats.set_stat lifeskillstatistic_manners -1
Just like that. Make sure it says -1 Hit enter
You'll see the red negative signs above your sims head, even as a YA, and they should stop constantly trying to wash dishes. This should work until devs fix this issue for us.