I don't know wether VSync works properly or not in this game since i don't use it, however first make sure that the game is running in proper Fullscreen mode. It seems to revert to Windows Borderless with every restart despite showing "Fullscreen", which might cause this issue.
As a Pascal user if you want to use Vsync you should be using Fast Sync in the Nvidia Control panel, it is superior in every way compared to vanilla V-sync.
It caps the game at 2x Refresh rate, only has 1 frame of input lag, compared to V-syncs 3 frames. But first you need to make sure the game is running in Fullscreen or it won't work, neither will Vsync as you have found out.