So I just updated Forza today, and tried to launch it from Razer and nothing happened. I removed the game and refreshed to see if it would show up, and it didn't. I made a desktop shortcut for the game and pressed the "+" icon in Cortex and it still didn't show up. I can't find anything in the "Browse" option either.
As seen here Forza Horizon 4 doesn't show up in the application list (There isn't even any "F" apps)