We have determined that there are areas in Alaska and Canada north of 59 degrees latitude where ForeFlight Mobile can display a lower terrain height than the actual value. This terrain information is used inside ForeFlight Mobile in the Terrain Map, Hazard Advisor, Terrain Profile, and the AGL and MSA cockpit instruments. This impacts geographical areas north of 59 degrees latitude, which includes the majority of Alaska and northern areas of Canada.
We are investigating the issue and will release a fix as soon as possible.