Dirt 4 on 5x1p display

[ninilefufu]

Hello, i'm french and i'm sorry for my English language…

i have five screen display (5x1p) and a RX VEGA 56 with hube,
assetto corsa, forza 7 work correcly but dirt 4 don't start and crash.
on 3 screen (3x1p) that work !!?
i'm on Windows 10 64 bits and all drivers and directx … are ok

Have you a solution for me ?

thanks