Issue with Vulkan framerate on Gsync monitor and Nvidia 560 drivers

[petran79]

My system specs are Windows 10, MSI GTX 1080 GPU and Asus Rog 34 Gsync monitor.

1. I set Gsync framelimit in Nvidia cpl at 97 fps (Monitor supports 100 hz max) and force vsync to apps for Gsync to work.
2. I pick Vulkan in Retroarch and enable the Gsync/Freesync sync option.
3. With Nvidia 551 drivers, Retroarch Vulkan reports 97 fps on the menu and games run at 60 fps speed as they should. However with Nvidia 560 drivers, Retroarch Vulkan display 48 fps instead and games run at 48 fps too. Vsync interval is at 2.
4. Only solution, because I also use shaders, is to use glcore driver instead. If I want to use Vulkan I have to completely disable vsync on Retroarch. Then fps appears as 97 and games run at 60 fps again.

I am using 1.19.1 but issue appears in previous versions too