Tank sensors option missing from Cerbo Setup

I was running classic Touch 70 UI and the three tank level displays began reading erratically over time. They then all failed to display at all. In Setup I could not see them as devices. Upgraded to the new UI and same problem. In fact the Setup menu item for the sensors does not even appear. Only thing I can find online similar is a faulty Cerbo. Checked connections and all OK. Any advice appreciated. Cerbo is about 2.5 years old.