Reproduction steps:
1. Open the attached project "sorting.zip";
2. Open the Test scene;
3. Open the Frame debugger and run it on this scene;
4. Select the material1 or material2 and change the render queue to 2450;
5. Observe the Frame debugger results.

Expected results: objects using same material (material1 or material2) will be rendered in 2 draw calls, before and after changing the render queue. (screenshot 3)
Actual results: if the render queue is set to 3000, objects are rendered in a chaotic way. (screenshot 1)

Reproduced on: 2017.1.4p1, 2017.2.3p1, 2017.4.5f1, 2018.1.4f1, 2018.2.0b8. 2018.3.0a1.
Note: in the 2018.x versions, objects are rendered a little bit differently, attaching screenshots 4 and 5.