The Pathfinding for Villagers causes them to try going through corners, and windows. They also highly dislike slabs, even now. If they however reach where they are trying to go (in some cases, are their beds) If they somehow end up on top of their bed, they don't sleep in it. It's only after you push them off will they get into it (almost immediately I might add.

Images

1. The Villagers attempt to recreate that one scene from Star Wars: Episode III – Revenge of the Sith. By getting to higher ground in an attempt to get to their beds.
2. They all cram into corners thinking that they have the ability to clip straight through, or because they think it's the quicker option (in some cases, they would be right).
3. The optimal entry point into the building. (Either the complicated structure design, or the single slab rules this out as an acceptable entry point.

I do apologize if this is a duplicate of one or more bug reports, but I feel as if this hasn't been getting enough attention, I may have also discovered some other flaws. i.e. the high ground, and the spiral staircase structure.