I have found only a single reference to someone complaining about the same problem online and they talked about changing their display density. I changed it from 480 to 445 and that made no difference so I reverted it.
I recently pulled out my Google Cardboard after not playing with it for awhile so I could show it to a friend and when I did so I at first thought nothing was on the screen until I realized the icons were shrunk really small and sat at the bottom of the screen. I'm on the latest CM11 nightly and I know the cardboard app has been updated since the last time I used it. Possibly related: I have noticed small text/icons in the Hangouts app in the popup menu where you select SMS/Hangouts to message a user. Does anyone know if this is fixable? I'll attach a screenshot in case it helps.