Hi Dennis,
Thanks a lot for reaching out.
To handle the edge points you must first be in the Camera Overlay option (1). From this display mode you can select the camera you want and add an edge point to it.
Maybe it´s a viewer problem. Please, make sure that the stereo mode is not active. Also, please, check if the align tool is not selected.
I attach this incredible tutorial made by my colleagues where the use of this tool is explained in more detail.
Finally, if the problem still exists, you can write us a ticket to our support portal so that we can treat your case in a more specific way and investigate the causes.
I hope this information can help you.
Best regards.
Daniel