Structure Build Order Prohibits Completion
I did this with a prefab design, but I'm pretty sure it will happen with any building, under the right conditions. The reader's digest of the problem is, when the right conditions are met, buildings cannot be completed without modifications to the surrounding terrain in order to enable Hearthlings to access impossible-to-reach places.
Steps to reproduce:
1) Find a cliff face that is low enough to fit under the roof overhang of your building design, but high enough to block at least one wall. This is possible to find without terrain modification, using the variable heights of the naturally-occurring cliff faces.
2) Place the building flush up against the cliff face with no block space in between. The roof will hang over.
3) Inside the structure, place furnishings flush up against the wall which has been positioned against the cliff face.
4) Have at least some of these furnishings on hand, and hearthlings available to place them, before initiating structure construction.
5) Observe the furnishings being placed such that they block Hearthling's ability to build the structure between the furnishing and the cliff face.
6) Hearthlings will complete as much of the structure as possible before ignoring it. To complete the build, it is necessary to remove 1 block deep of cliff face terrain behind the structure so that Hearthlings can place the blocked portions behind the furnishings.
Please note: If you do not have the furnishings on hand when construction begins, you may not be able to replicate. Indeed, the same building, placed in the same way, immediately to the right in the screenshots below completed fine, because I had not yet begun maintaining a reserve of beds.
Hearthlings would observe a build order that does not result in blocking their own progress, and the building would complete without intervention, OR, I would not be allowed to place the building in this way at all.
Construction is halted and then ignored until the player removes the offending terrain.
Note the 1-block gaps behind each pre-defined (mean) bed in this prefab sleeping quarters.
Note how, once I've removed one layer of cliff face behind the structure, construction immediately resumes.
See this issue for savegame and logfile. Timestamps available upon request.
Versions and Mods:
Alpha 12, Release 465 (x64)
Windows 10 x64