When processing faces detected I accidentally selected a group of already named faces together with unnamed face regions that could be removed and then hit the delete button. Unfortunately I only found it when it was too late to undo far enough back. It means that for a couple of persons LR has deleted all face regions (one person with already 400+ identifications).
Also, I was processing these with the complete catalog selected, so it is not easy to go back a couple of folders/collections and redo them.
As far as I could find there is no way to tell LR to reinvestigate as set of photos for faces. Or am I missing something?
Lots of people have asked about this. Please add your vote and opinion to this topic in the official Adobe feedback forum: Lightroom 6/CC - Allow facial recognition feature to re-index a folder/collection