Canvas UI does not render in GVR (Google Cardboard) in Unity 5.3.5

Question

Background

I am using Unity3D 5.3.5 to develop a Google VR (Cardboard) project

Introduction

I added a canvas button to my scene. It shows up in scene mode and sometimes in Game mode but never when I run the project

What I have tried

1. Turning off Direct Render for Main Camera
2. Setting up Render Mode of canvas to World Space
3. Adding Main Camera to Event Camera

Observations

1. Button shows up in Scene and Game Mode but not during Play mode
2. Though the UI does not show up, Physics Raycaster in the reticle hits the button.

Screenshots Below

Answer 1

This is a Unity bug. In the forums they mentioned it will be fixed in 5.3.5p5.

Its also noted in known issues for gvr:

Starting with 5.3.4p2, a bug in Unity prevents rendering World Space uGUI Canvases into a RenderTexture

https://developers.google.com/vr/unity/release-notes#v080_initial_release

It works in older version(5.3.4f1), if you need to test it right now.