I am using Unity 5 and the built in GUI tools. My static GUI shows up just fine which makes me think it's not a text/font issue or some such. Again, it all looks good in the Unity editor when I hit Play.
I have tried the different canvas options as far as what space to work in and how to scale. I have messed with the build options. I have tried turning batching off. I have tried building for Android 4 through 5. (Ice Cream, Jelly Bean, etc) I have tried turning dynamic text on and off. I have ensured the Buttons and text are made to be children of the canvas. I have only uploaded the game onto my Galaxy Note 4. I moved my background texture out of screen space in case it somehow covered the buttons on Android.