I ran into this recently, as well. The behavior that I was seeing was that unity would return an empty string (or null, I forget which) for mKeyboard.text the frame *before* the keyboard was deactivated. I worked around it by caching the last non-empty string and which frame the text was cleared on, so if the keyboard was deactivated on the very next frame, I could restore the text to what it was supposed to be. All of this was conditional on android only, since iOS works fine.