Reproduction steps:
1. Open the attached project;
2. Open the scene "MainScene";
3. Enter Play mode;
4. Move Main Camera along x axis;

Actual result: the new gameobjects do not instantiate and an error "Enabling or adding a Renderer during rendering; this is not allowed. Renderer '...' will not be added." shows up.
Expected result: the new gameobjects should be instantiate.

Reproduced with: 5.6.0b1, 5.6.0p3, 2017.1.0b2
Not reproducible with: 5.5.0f1, 5.5.3p1, 5.6.0a1
Regression introduced in 5.6.0b1