WebDriverAgent failed to connect (shows ECONNREFUSED) in simulator

Hi, I’m currently facing the issue where running my scripts in iOS device fails due to ECONNREFUSED by WebDriverAgent. The scripts are not continued as it couldn’t initite the webdriver agent. But everything works as expected when I build using xcodebuild. Could you please help me figure out the issue?

As for your reference, I’m using:
Katalon Studio 7.9.1
iOS Simulator 14.3/12.1
Xcode 12.3
Mac OS Big Sur 11.1
Appium 1.20.2

Hope anyone can assist me with this. Thank you in advance!