Ran into some strangeness with the GPS altitude on the latest firmware.
On initial bootup, GPS gets a 3D fix, and the altitude is correct on apmplanner.
Taking off and flying, the altitude remains fixed at the same level (does not increase)
Trying to fly a flight plan, it will climb over any assigned altitudes at waypoints (because the ardupilot must think it's still at ground level, and keep trying to attain say 100m.
Was working OK earlier - but no idea what changed. - will revert back to older code to see if it changes things.
Any recommendations on where to start looking?