Comment 22 for bug 241000

Resetting the bluez package did NOT fix the problem.
  Removing the bluez package(s), removing /var/lib/bluetooth and re-installing.

  sudo apt remove --purge bluez
  rm -rf /var/lib/bluetooth
  sudo apt install bluez gnome-bluetooth gnome-bluetooth-sendto

The bluetooth system need to be started, and this empties the list of discovered bluetoothe devices,
but the popup for the keyboard auth number disappears again.