I've noticed that since iOS 11, when setting the headingOrientation property of the Location Manager to CLDeviceOrientationPortraitUpsideDown the location manager returns wrong heading values. When the device is facing north the location manager returns south as the heading in this case. Up to and including iOS 10, this works correct and as expected. Since iOS 11 I do get wrong values.
A workaround would be to set the value for headingOrientation to CLDeviceOrientationPortrait when the device is in upside-down orientation, but of course only under iOS 11. iOS 12 seems to have the same issue.
Is this is new policy of the iOS, which I have missed, or is this a bug?