I am trying to simulate the locations, using a gpx file.
The file does not work in the Xcode nor does it show any error.
The file size is 1.1 MB , has a tracking
I noticed the same issue (Xcode 9.2). If you are adding the .gpx file through the status bar at the bottom and it's not appearing:
Drag and drop the .gpx file directly in your project navigator window on the left (where all your program files are)
and it should then appear in the drop-down simulator icon.