Is it me or do the monsters seem to be focusing on Joey? The snake could certainly get up the tree - it climbs up the walls and ceiling - and it followed Jude partway up before stopping to chase Joey, so it knows he's there, but instead goes to cut the power instead of going to eat him. The flying ones could certainly reach him, and don't go near him; they have no eyes but sense Joey's flashlight in the kitchen battle, so they could probably "see" him when he flashes the lantern.

I mean, the snake chases Joey since she seems easier to get than climbing up, and Jude implies he’s undetected and kind of remaining hidden in the treehouse.