With Soft Proofing enabled, the first time that you make a change to your image, Lightroom presents a dialog asking if you want to “Create virtual copy for soft proofing?” If you choose “Create Proof Copy”, Lightroom automatically creates a virtual copy allowing you to preserve your previous settings (in the master file), and create a new rendition (or version) tailored to the specific soft proofing options that you choose.
If you choose “Make this the Proof” Lightroom will make the changes on the master file.
When I select one of the options (say 100% White), only then does the "Soft Proofing" panel appear, but still nothing works. Is there something I need to turn on to use it?
You need to create a Proof setup
Please refer Soft Proofing in Lightroom - Scot Baston | TipSquirrel and let us know if that helps.
Tried that and after I create the copy, where the Histogram tab was now say Soft Proofing and there is nothing in the histogram window, and the small icons in the upper right and left that should tun into a monitor and paper, are still and up/down arrows. If I click in the histogram window, my normal histogram appears and the main large preview of my RAW file goes grey with no image. I have tried un-installing and re-installing with the same results.
Try disabling the GPU. LR / Edit / Prefs / Performance – uncheck Use Graphics Processor.
That was the problem! Many thanks.