I have searched here with no result, I can't find any similar problems.
I have an APM 1.4, GPS, MAG, Airspeed sensor, MinimOSD and XBees. I'm running the latest MP and Arduplane V2.7 firmware in the APM.
The problem is my Altitude does not change in flight. If set to absolute it reads approx. HMSL zero'd it hangs on zero. Airspeed indicates changes and is somewhere in the vicinity of ground speed.
On boot in the shed (no GPS lock) gentle pressure on pitot rolls the ASI up and curiously rolls the AH towards the ground, gentle suction around the pitot port rolls the ASI up and also results in the AH pitching down. With GPS lock the attitude does not change with the suck blow tests.
I have tried changing various check boxes relating to Altitude in the flight planner with no result.
I figure this is just finger trouble as to me the sensors appear to work