I just signed up and cannot post attachments. However, I think I figured it out.
There’s a 4x8 ledge adjacent to the corner of the house. Even though none of the building is obstructed, this is probably the problem. 1 scaffolding is stuck up top. The hearthlings will not place the inner lantern, outer lantern, beds, or the door, and leave the structure almost finished. This happens regardless if I cancel all existing tasks(excluding the trapper) or not.
BTW, I’d love to make building templates like you guys do(with fancy objects, and alternate coloring of some areas of the structure). Will the upcoming editor allow that?