I should prefix this by saying, I don't think it is a big issue.
Mostly, the logic works as you describe. But there are defiantly occasions when it doesn't. These seem to be for tracks that are sinuous. We get such tracks here when vessels enter the river from the sound and need to navigate around the island and shallows.
In the images
I've attached, you can see the class B vessel Pandora. Pan 1 shows the "head" of the track. Pan 2 shows the whole track (20min). Pan 3 shows the middle of the track which has neither the vessel nor the first point visible.
This is an example of the track remaining visible when the rules say it shouldn't. I don't think I've seen the reverse but I'll keep an eye out.
I've also seen this with class A vessels.
Originally Posted by bdbcat
The logic condition is "or".
A track will be shown if the oldest track point is on screen
, even if the target itself is not on screen