Nexus 5 Android 5.1, why doesn't my Google camera have a flash button?

[AC Question]

Nexus 5 Android 5.1 Google Camera No Flash Button

I recently Factory Resetted my Nexus 5 Running Android 5.1.1. Since then the Google Camera app does not have a flash button or icon. But the flash is working in Auto Mode. There are only 4 button in the app; timer, grid, HDR and change camera.
How do I get back the button?
Thanks in advane