Same Issue I have but seems no one i Adobe is able to solve. Maybe in the meanwhile you have fixed
I question why it is necessary that you should see it under the histogram when the originals are available?
But -Yes, you should see an indication if both originals and smart previews exist! Maybe a Preferences reset would fix?
1. Originals only
2. Originals and Smart Previews
3. Smart Previews only (Originals are not available- On another drive/computer, or even moved, re-named, using OS)
I only see point 1. Original only
What images did you have selected when you built the smart previews? A folder, Some, All,...?
Are you viewing a selected image that did not have a smart preview built?
Why are you building smart previews?
I do not know an answer for you, but trying to help!
I have build Sp for all and no one have been left.
Why are you building the smart previews?