LNAV Not Working Properly In The Boeing 747-800

[hobanagerik]

That sounds like the approach fly-back bug, or maybe a variant of it.

Approach flyback bug - Not fixed as stated in SU5

Please upvote and link any threads related to the issue of loading an approach in a GPS equipped aircraft it n will fly back to the last waypoint flown and lockout any further editing of the flightplan. Original thread here: Hopefully we can get this fixed.