Iron Citadel Signal Bug?

Sorry to bother everyone. I've reached the endgame of this game and received a patch that allows me to see citadels in the fog. However, I only see orange and yellow lights appearing in the fog, and no matter how I travel, I can't find the Iron Citadel. Currently, I’ve found 3 orange lights and 3 red lights in the fog and have completed the Copper and Stone quests, but the Iron Citadel is still nowhere to be found. I wanted to rely on a guiding light, but it doesn’t appear on the map at all.