Hi @jonathan.loh,
The first thing I’d recommend if you’re using Xcode 10 is to upgrade Appium to 1.8.2-beta:
npm install -g appium@1.8.2-beta
It looks like you’ve done a lot of the troubleshooting tips normally recommended. There are a couple more here, including editing your settings file to hardcode your physical device id:
Hope this helps,
Chris