Ok, so TurdlyPoop, the OP, is me.
I forgot my username when I posted that. Sorry.
Any way, I've been playing the game a bit more, and notice that this usually happens when my sim has to change clothes. Showering, changing diapers, going to bed, etc. They just stand there before doing the changing clothes animation.
Hmmmm. Sometimes, though, it just happens at the photo booth.
Or when she's supposed to be filling up the dog's bowl.
And I don't have the Tree of Prosperity. Or any store content really.