The Vulkan renderer seems to produce undesired behaviours when V Sync Count is set to anything but Don't Sync. These behaviours don't appear when using other Graphics APIs with the same settings. The attached project contains two examples using 2018.2.0a5.

I've tested this on 2017.3 and the undesired behavior actually always occurs on that version, no matter what v sync setting you use, so this isn't a regression.

Example A: Particles

1. Open the attached project
2. Build the scene "11_Particles" as a Windows Standalone with Vulkan
3. When booting the player, select the quality setting "Fantastic - No V Sync" from the launcher
4. When the scene loads, observe the "Emit over distance" particle system. This is the desired behaviour
5. Restart the player and choose the quality setting "Fantastic - Every V Blank"
6. When the scene loads, observe the "Emit over distance" particle system again

Example B: 3D Physics

1. Open the attached project
2. Build the scene "09_3D physics" as a Windows Standalone with Vulkan
3. When booting the player, select the quality setting "Fantastic - No V Sync" from the launcher
4. When the scene loads, watch the colliders light up in the "Collider Stay" section. This is desired behaviour.
5. Restart the player and choose the quality setting "Fantastic - Every V Blank"
6. When the scene loads, observe the "Collider Stay" section again