Adobe Digital Editions 4.5.1 installed, PC authorized with my Adobe ID as well as my Samsung Galaxy Tab4 Nook, but ADE does not recognize my Nook. Unable to transfer ebooks from PC to Nook.

I did not try an earlier version of ADE.  However,  checked to make sure the Nook software had all updates installed.......

I can see the device and file folders on my PC through Explorer.  However, it does not show as a media device that I need to eject safely when disconnecting.