Unfortunately for me, I started to have exactly the same problem after today maintenance. On the Start Screen game-in cursor replaces with system one and the game interface doesn't react to it at all (so the only way to exit is by using Task Manager and killing the task).
It appears for me in the full screen mode, but reset to default settings (Windowed mode) didn't help either, the problem repeated, both in DX11 and DX9 modes.

I use Razer Naga Chroma mouse and my OS is Windows 10 Pro.
Here is the link to my System Information from FF14 client, if it helps: https://pastebin.com/8FYzuxrV