Problem: I have a contour plot with both lines and flood. Contour flooding shows up fine on all parts of my zone but for some areas the contour lines are not drawn.
Solution: If you have a very dense grid the contour lines may be reaching the default limits of the number of points to use to draw a line. To fix this, add this command to the tecplot.cfg file:
$!Limits MaxPtsInALine = 100000
This file is located in the Tecplot 360/Focus installation directory.