Hello leobrenes2,
You are loading calibration to the isolated variable that is not connected to the original images.
If you've got only one camera calibration group, you need to load the calibration via sensor instance:
path = PhotoScan.app.getOpenFileName("Specify XML location:")
sensor = chunk.sensors[0]
calib = PhotoScan.Calibration()
calib.load(path, "xml")
sensor.user_calib = calib