when building rooms ive come across the issue if there is an item on the ground within the room it will delete the supposed floor tile that should be placed there and without dismantling the room and restarting from scratch there is no way for place those floor tiles to fill in the floor.
#Add room flooring as buildable option
last lake
fading talon
I've ran into this often when slightly expanding rooms to get non-squares as well, I haven't quite figured out the "tick" logic to get it to rebuild the floors, but it does exist as I've had it auto queue the floors to be rebuilt.