I've noticed something with my airline in R1. I own 35 hubs, most of which were purchased in game year 1959. The buildings held a value on the graph of "2005" until the Nov 1 of game year 1961. Starting on Dec 1 of game year 1961 that value dropped to "0" and has remained at "0" since then. Is this by design or is it some sort of error?