I can use the View > Update previews feature to successfully update the thumbnails in the address book when the lid is closed and the viewer is "unresponsive". So it looks like interactions on the viewer are taking place (mouse and keyboard actions), but the viewer is not updating the image.
Good news... I enabled legacy mode and restarted the notebook with the lid opened. I connected with the viewer and confirmed that with lid open operation is normal. Then I closed the lid, and the viewer continued to function normally!
My last test was to restart the computer with the lid closed and confirm that the viewer was still functional, which it was.
It seems legacy mode was the answer for my issue. Thanks very much for the excellent tech support!
If the lid on the laptop is closed, I get a black screen on the remote viewer. Note that closing the lid during an active remote viewer session interrupts the session - the desktop on the viewer is no longer responsive.
In this case, I'm using remote utilities on a Dell Inspiron 7348 2-in-1 notebook running Windows 10 Pro.
Note that Windows Remote Desktop works regardless of whether the lid is opened or closed. I'm pretty sure this isn't a power-down or sleep mode issue.
I have tried with the remote utilities display driver installed and not installed. No change in behavior, even after restarting the computer.