Photos app keeps rescanning, deletes names
After updating to iOS11 on my iPhone, Photos started scanning the faces in my existing photo albums. I plugged the iPhone in for a few nights and locked it so that eventually all 4000+ photos had been scanned. Then I set about naming the faces it had found, assigning new Key Photos to them, etc. All was fine until the first time I recharged my iPhone afterwards... the next morning, all my people names had disappeared and all the Key Photos had changed back to default ones chosen by the Photos app. I tried once again, naming various people and reassigning Key Photos; again, the first time I plugged my iPhone in after that to recharge while it was locked, all the face names and key photo choices reverted to default. Happens every time. Note: I prefer not to turn on iCloud Photo Library and, consequently, all of my photos are stored locally on my iPhone.
iPhone 6s, iOS 11.0.3