The Cubemap type of OVROverlay not working with Oculus Utilities 1.18.1

Hello, we are built a demo scene with OVRCameraRig and OVROverlay object
In OVROverlay, we set Current Overlay Shape to Cubemap, and assign two textures

We run this scene on Android, we can't see the cubemap texture.

If we downgrade OculusUtilities to 1.15.0. then it works fine.

Demo project at:   https://github.com/sycx/CubemapOverlay.git

- master branch:  with OculusUtilities 1.18.1
- plugin_1.15.0 branch:  with OculusUtilities 1.15.0