It is. Are you sure you have gsync enabled? I get no screen tearing whatsoever in BF1 with my gsync monitor as long as the framerate is below the refresh rate of the monitor.
Are you using a display port cable? Gsync will only work through display port. Also make sure Gsync is enabled in nvidia control panel for full screen or fullscreen and windowed mode if you use windowed or borderless mode in bf1.