Like the title says, tap on the building, not Maggie.
I have seen one person post that when Maggie was on Lard Lads Donuts shop (she appears inside the donut) that he had to tap directly on Maggie to find her, but I cannot confirm that because so far I have only found her on top of Blue Houses in my games (7 times).
I'm QUITE sure that's already been tried by a lot of players many, many, many times. The f'ing game is just busted, garbage programming et al!!! Hell, if the game can already tell the difference between clicking a character standing in front of a building, a "$", the building itself and an imaginary bear WTF is the Maggie click detection so fundamentally flawed?!? Also, it's "Find Maggie" not "Find Building"!