Steps to repro:

1. Open attached project and 'Main' scene;
2. Notice that there is 'Rock Spawner' gameobject that spawns instanced objects to the scene when launching. The shader for spawned object's material has explicitly disabled instancing flag.;
2. Launch the project.

Expected result:
- Instanced objects are not rendered;
- 'Material needs to enable instancing for use with DrawMeshInstanced' exception should be shown in the console.

Actual result:
- Objects are rendered;
- No error is shown in the console.

See attached video.

Notes:
- The bug creates inconsistency within different types of DrawMeshInstanced API in terms of new instancing enabled workflow;
- Reproducible in 2017.1.0b1, 2017.1.0a6, 5.6.0f3;
- Reproducible on Windows 10 and OSX 10.12.3;
- Couldn't test in 5.5 since new instancing workflow was introduced in 5.6.0.