Sims washing hands in sink in different bathroom (Patch 1.117.288)

Having the same issue.

Sim uses toilet on second floor and then walks down on first floor to use the sink there.

BUT: i noticed this: the issue began, as i upgraded the sink on the first floor.As i also upgraded the sink on the second floor too, they began to use the nearest one again.

Update from next day: today my Sims are back to using the sink on the other "wrong" floor.......

I can't seem to find a solution for this. Am I missing it?

My sims go to a different sink to do everything. In kitchen? Go to bathroom to wash dishes.
Changed the sink type.
But the using bathroom and traveling across property to wash in another room is super annoying.

If you think you see an example of this bug, then it's good to check whether your Sims will wash their hands in the sink if you specifically tell them to use the sink they avoided. After remodeling their master suite, I noticed that my Sims were avoiding one of the sinks. It turned out that they wouldn't use that sink even when I told them to.

In build mode, I figured out why. I had installed that sink backwards, facing the wall rather than facing out into the bathroom. No wonder they wouldn't use it.

With that said, I am still seeing the bug occasionally. But there are now 2 Sims in the household, and it seems to happen most when I tell one Sim to use the bathroom, and then focus on the other Sim for a while. Then I notice that the other Sim is washing his/her hands in a sink on a different floor of their home.

I've been seeing other weird routing issues as well. For example, there is at least one NanoCan trash can on every floor, but my Sims sometimes take trash to one on a different floor. Or I'll have a parent Sim put an infant Sim in the crib upstairs, and the parent will go upstairs to the crib without the infant, then go back downstairs to pick up the infant, then go back upstairs to put the infant in the crib.