[a18 dev] some auto-placed scaffolding/ladders not being taken down

Not a full report yet, but noticed that singular auto-placed scaffolding/ladders are not taken down even after the building is complete (strangely, only one per building). Still trying to replicate the problem. It appeared twice in one of my modular building (building made up of separate templates), but when I tried to build a similar module separately. the problem did not happen.

EDIT: just to add, I’ve used a similar setup in a17 with 100% no problem (“perfected” the setup to avoid the usual building issues, and have reused similar setup in a save game without getting building halts or leftover scaffolding/ladder. roughly x16)

EDIT: more observations, but still no clear reason/cause

Usually, when building (at least in a17), the foundation is built first, then the whole pillars (edges of wall), before the actual walls are built layer by layer, then the floor of the level above and so on so forth.

In this particular case, the pillar where the leftover scaffolding/ladder is behaves strangely. The entire pillar, from level1, the tile on the pillar at level 2 floor, the pillar above in level 2, and the tile above that pillar at level 3 floor is built all at one go, even when the floors of level 1 has not been finished building.

When building is complete and teardown commences, the scaffolding (of the left over) is reduced to the level of the floor of level 2 (ONE LEVEL ABOVE the one shown in above image). Then the ENTIRE ladder is removed. But ANOTHER ladder is built at the same spot to the level of the scaffolding. Then other removals of other ladder/scaffolding takes place and what remains is the two but somehow reduced by 1 tile (i missed the exact instance that happened).

Am going to rerun the same thing again from an earlier save to see if that happens, and to try to create more intermediate save that may reproduce the above…

EDIT: I think I have a save that recreates the problem.
1471148448311.zip (6.8 MB)

EDIT: A workaround that seems to work (only tried once so far), is to manually build a ladder at the “problem spot”. (Since ladder cannot be built against ghost wall, I had to place a crate in the building design, place the ladder, then remove the crate).