Rocket League Multi monitor 3 player screen goes black

I used this solution to play rocket league split screen using both my monitors. Now I wanted to play with two friends so I added a third controller. This works fine until the game starts. Then you can still hear sound. From the sound I can hear that the controller input also works. Here are some pictures that might help visualisering what I mean.

I also tried starting a Exhibition match and adding the extra players after starting the match. This has the same result when the third player is added.

Solution 1:

I am answering this question on request of @HazyKingdom. Please let it be known that the answer was found by reddit/youtube user vi9ke.

1. Go to you Display settings.
2. Multiply the width of your smallest screen.
3. Remember or write down the the value from step 2 and the height of your smallest screen.
4. Open File Explorer.
5. Go to your documents folder (Probably C:\Users\{User}\Documents unless you have changed this yourself).
6. Go further until you are at C:\Users\{User}\Documents\My Games\Rocket League\TAGame\Config.
7. Here you want to create a copy of TASystemSettings.ini so when you make a mistake you can revert your changes.
8. Open TASystemSettings.ini in your preferred text editor.
9. On line 62 there is a value called 'ResX' change the value to the value you found in step 2.
10. On line 63 there is a value called 'ResY' change the value to the height of your smallest screen (step 3).
11. Start up RocketLeague
12. Go to Options > Video and set 'Windowmode' to windowed or borderless (whatever works best for you).
13. Go to Options > Misc and make sure 'Horizontal Splitscreen' is unchecked.
14. If during the game you see objects not being rendered or a black screen. Go to Options > Video and set 'Render Quality' to 'High Quality'.

This answer is tested on Windows 10.