Why might I not be losing weight on the bowflex body leanness plan?

Not enough time. The most common cause is that people give up too quickly because they become discouraged. Base success on the number of months using the bowflex rather than pounds lost.
You might be. Your weight might be stable because you are gaining lean body mass and burning the fat. Only way to know is to have a body analysis done that can give you a percentage of lean body mass.
Excercise. Is only one part of losing weight. You also have to eat healthy and decrease your overall calories. If also you increase your muscle mass despite losing fat your weight may not change. Easy way to know without body composition analysis is losing part size or your parts becoming too large for you.