Are shadows disabled on Nexus Player under OpenGL ES 2.0 (but enabled under OpenGL ES 3.0)?

I am building a game that I would like to be able to run on all android devices, including android tv devices. I have been testing on the Nexus Player and I have found that shadows refuse to work at all under OpenGL ES 2.0, but work fine under OpenGL ES 3.0.

One immeadiate solution to this is to use 'Automatic' graphics selection which in principal works. However, when I enable 'Automatic' graphics and test on a Nexus 5 phone, which has OpenGL 3.0 support, it graphically breaks my game (which is running perfectly fine on e OpenGL ES 2.0).

So what can I do to solve this issue?