I spent the day trying to figure this out myself. After failing the check ride several times and continuously hearing "check your altitude", I edited the practice mission to daytime and made passes each time increasing altitude 300 ft starting from 5k over target 1. Despite the documentation and posts here saying 6k ft, I didn't get the "Well done, target in sight" response until 7800 ft. I finally finished the check ride dropping each flare from 8100ft and .2 miles from each waypoint at 300 kts.