Why is my SIMATIC WinCC OA OPERATOR app not working after I reinstalled it on my iPhone, even though it worked perfectly fine in the past?

Due to improved license security each installation of the SIMATIC WinCC OA OPERATOR uses an unique identification key and therefore your device must be newly approved for connecting to the mobile app server.
Please contact your administrator to regain your access to the mobile app server.

Note for administrators: The old installation of the SIMATIC WinCC OA OPERATOR still reserves a license slot and must be manually removed from the list of approved devices to regain the license.