False 'Unreachable'

Placed walls reading as unreachable despite being right next to built floor.

https://steamuserimages-a.akamaihd.net/ugc/1817763657640105548/557C34208B40A41828BFE94A9F98FEBD0595C8CA/?imw=5000&imh=5000&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false

It seems like there may be an issue with certain attributes of building that are set when you place it then never update afterward. I'm going to upload an issue re room detection that I wonder if it might be the same issue.