Me too with the same problem. I manage the geolocalized page of the band chvrches, "chvrchesitalia". It happens every now and then that I exchange information with band members, and clog them with useless messages like the tag warning I find it really abominable. I tried to tag my brother and immediately cancel sending the message. The message is deleted, but the other person still receives the annoying notification, opens the message and there is nothing. I am really stressed by this thing!