Hey there,
Thank you for sharing your issue with us here. My name is Michelle, and I am part of the Razer Cortex technical support team. I am happy to help you with your issue.
As the FPS overlay may cause the performance issue for some users when play games with unreal engine. In the latest update of Razer Cortex 10.10.4.0, we disabled the FPS overlay for such kind of games. That is why the overlay in Fortnite didn’t show.
Our engineering team is working on another way to fix this issue. It is estimated in the Q1 of 2024. We apologize for the inconvenience. Thank you for being patient.
Please feel free to let me know if you need further assistance.
Michelle