go into the iphone settings "app" then look for ballistic AE. scroll down to the "units of measure" section and select "atmosphere" at the bottom. choose "format" at then select Density Altitue. If you have the lastest version it will give you an error as seen in the previous post, until the update with the fix comes out soon. until then use the meteorological atmosphere setting.
I had done that already, but still not there. I just opened HUD, it shows DA, I load my bullet, it's gone. I go to make a new favorite and the DA is not even present...this is super aggravating and I have a decent amount of patience.