People View shows no files

[DONUSA]

I did facial recognitions for hundred of people and had thousands of recognized photos, which I could see in People view.  If I opened an individual photo, names would appear. 

Today, I opened the database after not using Photools for months and People view does not show any photos at all.  The only group I see is Unknown Persons and that has no files in it.  If I open an individual photo in Media Folders, there are also no names showing or even green boxes around faces.   

As a test, I selected a set of a few dozen photos from a wedding.  I manually ran facial recognition.  They then appeared in the Unknown Persons group in the People view.  When I tried to add a name it asks "Who is This" and all the names I had previously created are not there.

Essentially, it is like I never spent all those hours doing facial recognition.  Any idea what happened and how I might be able to restore my work? 

I opened a backup of the database on another drive and it is the same. 

[Mario]

This is very unusual.
The face data and person assignments are stored securely in the database. The only way to delete persons is manually, by the user, in the People View.
There is no command or workflow to remove all users. I don't see how IMatch could lose the links between faces and persons. Nothing similar was ever reported since this feature was introduced in 2020.

1. Please double-check that you open the right database.
2. Run a database diagnosis via Database menu > Database Tools to check the database for health.

I have really no idea where to even start looking for the source of such a problem.