"Override Game Mode" only works with "Use Separate Process" enabled

Override Game Mode only works when Using Separate Process

1. Create a Third Person Template Project
2. Delete the character from the level and save (otherwise it will auto-posess)
3. Create a blank sequence
4. Select Capture Movie
5. Disable Cinematic Mode
6. Set "Override Game Mode" to "Game Mode" (should be just a floating camera that controls with WASD)
7. Capture Movie

Result: Still uses the Third Person Game Mode
Expected: Uses "Game Mode" with the floating camera

8. Enable "Use Separate Process"
9. Capture Movie

Result: Uses "Game Mode"

Sequencer 4.12.4 Game Mode Override not working