I have noticed a strange bug with Villagers when they try to pathfind up a level in a building.

On our Realm, we have a custom building in which villagers are housed. There are staircases between floors, and the villagers travel between floors. However, when going up stairs, they have trouble pathfinding in a way that will let them enter the next level. Instead of proceeding up the stairs and then proceeding to their destination, they will sometimes approach the side of the stair case and jump up and down as if they can jump on top of the block.

In my testing, this only seems to happen when the block next to the stairs before the top step is a top slab. If the space next to the second or third step from the top is air or a full block, the villager will either pathfind around or jump at the right height to make it on top of the block next to the top step.

If I need to upload a small test world or more screenshots, let me know.