Lord Zheng's current skill level naturally doesn't allow him to sense the presence of so-and-so around him in advance. Moreover, with an existence like Prince Jingnan, unless the Sword Saint is present, it's difficult for others to perceive in advance.
This is also why, several times while Lord Zheng was talking, Prince Jingnan suddenly appeared.
His identity can make his outer guards silent;
His skill can avoid being sensed by most people;
However,
Even Lord Zheng, with his dullness, would not confuse the sound of boots hitting the ground.
This is just like how Ji Chengjue can still develop his "underground forces" under the eyes of the Yan Emperor. It's not that the Yan Emperor truly can't see, but their gaze is too high, often ignoring or not caring to see these little details.
"It's time to prepare."
Lord Zheng spoke.
A Ming responded, "So quick."
"The Chu people are beginning to shrink back."
