Villagers not recognizing new 'houses'

While trying to create a golem farm, and now during testing, I've found that no villagers seem to recognize houses as would be expected. when placing a solid block directly behind a door, which as far as I know counts as a minimal house, it is not detected or used by any villagers. After expanding it a little to a more classical house shape (pictured below), it is still not regognized, and the bed inside is unused.