I had a weird experience setting up one of my APM 2.6 controlled quads using Mission Planner 1.3.24 build 1.1.5574.33902 and Arducopter V3.2.1 )36b405fb). I set up wp1 as an ROI and added a total of 18 waypoints to circle the ROI, return to my landing point and land. As I have done in the past, I set my next to the last waypoint (#17) to the point I wanted the quad to land, clicked on "add below" for #18 and changed it to "land". The program then placed wp #18 thousands of miles away! I have attached 2 jpg files to illustrate.
What the heck happened?