iPhone app. Someone posts something. When looking at their message at the end of their message there is picture of a smiley face with a small plus sign on the top-right of the face. This implies to me that I can tap on that and add an emoji response to their message just like the desktop app does. Yet when I tap on it it just does nothing. Bug or am I using it wrong or interpreting what it's supposed to be doing wrong? There' nothing in the App Store preview and literally no help that I can find (why is that?).