I am copying what I posted to the official bug forum in hopes it will save someone a lot of frustration:
I am in the process of decorating The Spires castle. I noticed that when trying to place either deeded or customization (pavers, stone blocks) on the roof, it is impossible to do so if there is a container on the floor below. Initially I thought that the problem was with me stacking chests too high (stacks of 4) on the floor below. I was even able to open chests from the floor below by clicking on roof floor. However, removing the top chest from a stack did not help. Only completely removing the chests from the floor below allowed placement on the roof. This happened with metal chests, wooden chests of various kinds, wooden shelves, and academic bookcases. In one case I had to move a container that was located two floors below the roof. Once the decorations are placed on the roof, the containers can be returned to their previous positions without issues.
Until, or I should say IF they bother to fix this, the obvious work around is to decorate your castle starting at the roof and going down.
I am in the process of decorating The Spires castle. I noticed that when trying to place either deeded or customization (pavers, stone blocks) on the roof, it is impossible to do so if there is a container on the floor below. Initially I thought that the problem was with me stacking chests too high (stacks of 4) on the floor below. I was even able to open chests from the floor below by clicking on roof floor. However, removing the top chest from a stack did not help. Only completely removing the chests from the floor below allowed placement on the roof. This happened with metal chests, wooden chests of various kinds, wooden shelves, and academic bookcases. In one case I had to move a container that was located two floors below the roof. Once the decorations are placed on the roof, the containers can be returned to their previous positions without issues.
Until, or I should say IF they bother to fix this, the obvious work around is to decorate your castle starting at the roof and going down.