I spent hours yesterday swapping sensors between mine and my friends bike, it would work on his Wahoo but not mine. Now reading this its evident that he must not have updated his firmware 
I can also confirm that factory reset didn’t work, and like someone else said taking screenshots of the display pages really helped.
Have submitted a ticket to Wahoo this morning, but surely its an easy fix by rolling back the firmware to a previous version until a proper fix can be found ???