The savegame is saved in 0.16.1388, but since I was unsure if the save was started in that version, I started a new game (still on 1388) and this also happens there. It's the latest version in the Steam unstable branch.
Sorry, I should have included the build number in the post to begin with :/
Btw, this also happens with vents and doors, so probably everything that can be built over existing walls.
Sorry, I should have included the build number in the post to begin with :/
Btw, this also happens with vents and doors, so probably everything that can be built over existing walls.