To Reproduce:

1. Build and run the attached project with GLES2.
2. Observe that all materials are corrupted (it's just using Standart Shader)
(see attached screenshot)

Also you'll get these errors whe launching the app:

WARNING: Shader Unsupported: 'Standard' - Pass 'FORWARD' has no vertex shader
WARNING: Shader Unsupported: 'Standard' - Pass 'FORWARD_DELTA' has no vertex shader
WARNING: Shader Unsupported: 'Standard' - Pass 'SHADOWCASTER' has no vertex shader
WARNING: Shader Unsupported: 'Standard' - All passes removed

Not reproducible on Gles3 or Metal.