iMessage weird behavior

My daughter sent an iMessage with photo to my wife and to me—a group message. My wife and I each have our own iPhone and iPad. (Mine: iPhone 7 Max, iPad 6th Gen; hers: iPhone XR, iPad Air2.)

Here’s the weird stuff:

• On both of my devices AND on my wife’s iPhone, the message displays the photo with two little circular thumbnail images: photos of my wife (the other recipient) and our daughter (the sender). Perfectly normal stuff, right? However ... ,
• On my wife’s iPad, in that very same message, instead of those thumbnails we see “Unknown.” My daughter’s name does display just above the photo, hard left; but at the bottom we read, “The sender and other recipients are not in your contact list.” Then there’s the helpful button for “Report Junk.”

Both my daughter and I do appear in my wife’s Contacts. Can anyone explain this behavior on my wife’s iPad?