Problems with camera view window

Hi - I have a 3Mp HD USB camera on the hub connection with an MKS DLC v1.0 to Lightburn v1.2 running on Win 10

Initially everything was fine and the camera was detected and displayed in the camera window but after undocking and expanding the camera window to get a larger view, every subsequent time I started Lightburn when I try to activate the camera window nothing appears yet if I go into camera setup the live camera image is visible ?