Theme categories are used to label items which require that theme to be purcahsed. They are not for use for labelling contractor items. Please stop doing so. For example, it is appropriate to label Palazzo Michiel as Venice Theme, because it is grouped in the shop in the Venice Theme tab and requires Venice Theme to purchase. It is not appropriate to label Flame of Nations as Polar Theme, because the Flame of Nations is a contract reward, and has no theme associated with it in the Buyback shop. Valentina's station is set in the Polar Theme, but that does not mean all items associated with a contractor should be labelled with the associated theme.
So that I do not have to clean up after you, I would appreciate it if you would review the theme categories you have added to items to make sure the categories have been appropriately applied.