Anyone else having problems with the overlay not working in 4.01 (it wasn't working in 4.0 as well).
Can't turn it on with the key combo to show FPS.

In gog settings overlay in game is active?
Go into GOG settings icon (lelft upper corner) -> Settings -> Game Features -> at in game features tick the box "overlay"

If you have nVidia gpu you can check fps in geforce experience
In AMD in Adrenaline software overlay,

My recommended option for fps overlay is to use MSI afterburner + RTSS or FPS monitor, because sometimes steam or gog overlay can significantly reduce performance.

Thank you for the suggestions, I forgot to mention I know all these options and I don't want to use them, also, yes overlay setting is on in GOG.
I am pretty sure I am just asking for the problem with W3 and the gog overlay ingame, not for alternative ways to see FPS in a game in general.
The overlay ability to show fps in w3 has been appearing and disappearing with different patches and fixes since the next gen update, so if anyone has any idea specifically about this, or knows if CDPR are aware of the problem, would be nice to share it.

I see, but maybe performance impact it's reason that's why they disabled it. Dunno, i don't use it, just saying.