When you enter new system and you can see the planets the resources are still listed as unknown. If you order your scoutship to travel to a planet with unknown resources and select the planet before the ship reaches the planet you can't click on the newly discovered resources for information what they are. The information screen still believes you haven't been to there. If you deselect the planet and then select it again it works. Maybe a simple check if the planet was selected when explored, the game would reupdate it.