[TROUBLESHOOT] “Can’t find object” when trying to expand room or build wall

@NumeroLetter I am not experiencing that error on Bedlington Boathouse in my game.  I am, however, working with the build that came with the expansion pack.  Is it possible you placed a different build on that lot?  If so, there might be something problematic with the particular build you downloaded from the Gallery.  Try starting a new save and testing the original build that's on the lot.