What the hell?
The GM said so.
Do I understand correctly that from now on we will see all of the GM's NPCs on the map that have gone invisible, but we just won't be able to target them without revealing them first? So that we can deliberately step on their tile and expose them, since the GM/judge has that ability? Because that's not fair at all if not.
No, you understand incorrectly. It will be as it was before.