I have a 3440x1440 alienware 21:9 oled monitor. Competitive games give me way more fps at the 21:9 1080p resolution (2560x1080) on my system.
That being said, I opened nvidia control panel and added the resolution since it was not showing in display settings. After that it shows up in display settings and I can change my resolution to 2560x1080.
I just installed razer cortex and the custom resolution does NOT show up in optimze. It is trying to set my game settings to 3440x1440.
I did try uninstalling it and reinstalling. I also tried removing the custom resolution from nvidia control panel and re-adding it after I reinstalled cortex. Still no 2560x1080 resolution in cortex.
Just a quick edit. It does show the 2560x1080 resolution in league of legends and pubg so it appears this is only an issue in cyberpunk 2077.