After updateing to Win 10 1803 my Team Viewer 12 will start up and the screen disapears after a second. Icon disapears from the task bar. It still shows up in Task Manager and on a remote machne it's listed as on but will not accept a connection. I've reinstalled and tried as Admin. Same issue. It also does it during the install process. I believe it has something to do with Windows Defender.
I also reinstalled Win 10 1803 and Team Viewer worked fine until I activated Windows. Then it immediatly shut down Team Viewer.