If a game is set to play with 3 player splitscreen, starting the came will cause the viewport to go completely black. Does not occur with 2/4 players. Does not occur in standalone
1. Open UE4Editor (any project)
2. Open level BP
3. Add Event Begin Play node
4. Wire Begin Play into Sequence node
5. Wire "Then 0" and "Then 1" into a Create Player node
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-9825 in the post.