Kerbal Space Program

This one's been around for several versions, though I didn't find a bug report for it.

There is a second closely related bug here, which is that a "closest" approach is both at a point where the distance between the ship and target is decreasing, and before 1 full orbit from the ship's current position (assuming the expected behavior is to search up to 1 full orbit.)

Here's an example where there's a minmus encounter, and the map screen finds closest approaches before and after the encounter, while missing the encounter it's self(sometimes the game will flicker between finding the encounter and finding a close approach):