i created an adaptive family with two points.
to check i used a second family to visualize the corner points (the sphere).
i expected that the corner points are identical. but see yourself, ther two families do not meet.
i checked the coordniates, dynamo says they are identical!
any clue???
Peter.
It’s possible that a single point adaptive family reports its location from a family origin and not location of the point. What i would do is to edit the family and move the adaptive point inside of the family to where the two origin planes intersect. Try that, and let me know if that solves the mystery.
konrad, it is a 2 point adaptive family and from my experience the definition is right.
but the adaptive points do not coincide with the corner points of the box.
i am clueless as the reference lines are constructed with 3d snap to the adaptive points!
have a look:
konrad, i invested some time to check and found out, that it is just 
an issue with the revit display driver.
when exported to navisworks or solibri the family displays fine.
regards peter