Hi, How are you? I am Alan. I will be happy to assist you today. I appreciate your contact!
Some games have different full-screen modes: Exclusive Fullscreen and Fullscreen (Window). Try switching between these modes in the game settings to see if the overlay becomes visible.
Restart GeForce Experience services.
Press Win + R, type services.msc and press Enter.
Find "NVIDIA Display Container LS" and "NVIDIA LocalSystem Container".
Right-click on each one and select "Restart".
I hope this information helps. If you have any questions, please let me know and I'll be glad to assist you further.
Alan