iPhone SE iOS 12 - "This device supports screen sharing only"

First-time poster and I'm a little confused. As recently as a few months ago, I was able to provide my fiancee remote support via QuickSupport on her iPhone. Today, she had to get the phone replaced, but it's an identical model and has the most recent iOS update. Now, when I tried to connect so I could help her finish setting up the new phone, I see a pop-up bubble indicating that "this device supports screen sharing only". Why is it that I was able to remote control the exact same model of phone as recently as September of this year, but now, all of a sudden, it won't anymore? She really needs my assistance and screen sharing alone won't cut it.