That being said, I just looked it up in the manual and came up with this: All I can come up with is that I had inadvertently pressed 'Direct-To' on one of the fixes and had failed to ever select Activate Approach. I looked this up because I have recently been on an approach and gotten a warning message from the GNS (430/530) that 'approach has not been activated' even though I was navigating on a published segment of the approach course.
