Do you have your second monitor set up correctly?
So from my understanding.
* You have Photoshop running on your main monitor. Correct?
* You are then dragging open Photoshop projects/windows to your second monitor. Correct?
* But when you do this the images in the Photoshop project/window disappear. Correct?
Can you record yourself doing that with your phone and share the video. Just so we all understand what you are doing or what you are trying to do?