In my experience with epic the games they have that support controllers are xbox controllers only. So If you were or are using Playstation controllers this was my workaround. I am using DS4Windows (emulates a PS controller as an XBox Controller) and a batch file to launch DS4Windows then launch the epic game (requires replacing the path in launch box from the games executable to a .bat file) the batch file then monitors the game executable and upon exit kills DS4Windows and returns focus to BigBox/LaunchBox. let me know if this would be helpful and I would be happy to post the contents of the file along with how to configure it.
I could probably or someone else may be able to write this as a plugin, I just haven't had the time.
Example of Epic Game Lego Star Wars The Skywalker Saga using the batch file, although the game can and does utilize Xbox controllers, notice the prompts and such are for Playstation. I apologize ahead of time for some of the delays and choppiness of the video, it was recorded through a VNC connection to to my PC running LaunchBox, with me running through to the other room to pick up the PS4 controller.
diabolicdesigns.com/gaming/video/Epic_Games-PS4_Controller-LEGOS_SKYWALKER.mp4
