So I ran across a weird issue recently. I wanted to build a special building for each of my professions, like most normal villages do. In an effort to do this I built some nice little 7x7 (8x8 including walls) structures with a single door and a couple windows. Upon completion i gave the order to move the workstation into the structure, and nothing. For some reason no hearthling will move the workstation into the structure. The blueprint outline is showing up, the move icon is showing over the bench, but beyond that it’s just stuck. I’m not sure if this is a building size issue or just an overall build problem. I plan on testing it some more and will update.
Try undeploying the crafting bench (I think they will return it to the stockpile) and then build a building with it pre-placed in the building.
I think there are still some roaming bugs with placing furniture in buildings that are already built. Your issue could be unrelated but I’d be curious to see if pre-placing will work. That would at least let Team Radiant know the issue isn’t just that a workbench can’t go in a building anymore.