When I create an adjustment layer using Levels---and I make changes using an inverted mask, the histogram doesn't refresh. In fact, the small window is empty. Is this a bug in Photoshop or am I missing something.
Could you please post a screenshot with the pertinent Panels (Layers, Channels, Histogram, Options Bar, …) visible?
Is a Selections still active?
Can you manually refresh the Histogram?
Finally got it to work by closing and restarting LR---now all painted areas show in the histogram--Thanks so much