I noticed this when I first installed it and forgot to submit a ticket as it was only a minor niggle.
Has anyone tried to set the pressure manually? I have a few times at FL390 and the best I can get it down to is ~16,000ft.

There has been a few nasty accidents with pressure failures, there was a Beechcraft King Air 350 over here in Western Australia that flew for 5hrs up to Queensland before it was seen to go missing. All on board fell asleep and it stayed on course until she was out of fuel. IIRC they were cruising at FL250.
EDIT: It was a Super King Air 200. https://www.atsb.gov.au/publications/investigation_reports/2000/AAIR/aair200003771.aspx

Some really weird things can happen wrt to air pressure, I have spent some extensive time in hyperbaric chambers and have suffered a couple of oxygen fits. So it works both ways you can also have too much pressure/oxygen.
The scary part is that you don't feel it happening, one minute all is ok, next thing you know you're unconcious. When you wake up you know something has happened but have no idea what.