I tend to think now that 1/2 on the tank gauge is more like 2/3 of what LP the tank holds when "full" At that time, the range hood monitor was showing three lights out of four. (Shows four lights indicating full when the tank is full showing 3/4)
Somebody mentioned the confusion of "thirds" vs "quarters" between these two gauges in another thread. Anyway, it seems that the range hood monitor is a little "over" what is really there, while the tank gauge indicates less than what is there, so somewhere between should be close.
I agree it is all too silly. Another case where the people who invent these things have never gone RVing.