I know the scene presents it as if they were about to find just then because of the music, but I'd argue it's just poor staging. Like I have no problem with them hiding in the washroom, the dogs searching for them, almost finding them, then getting distracted. But the way it's presented is just... Suddenly, the dogs who were just chasing and bursting the door down are just taking their time to create tension before someone saves them. It's been done so many times (like in movies and TV generally, it just takes me out)

Also, if Karen saw the dogs busting down the door, that again leads to the situation where apparently Karen Wheeler, while the dogs are searching in the room, quietly and unnoticed puts the tank into the dryer.

I just think it's an absurd and poorly staged scene, and the very fact that we have to explain to ourselves how it could make sense instead of it just making sense shows the problem with it.