So since I've came back to FF14, with an upgraded PC now, I finally see a cap frame rate at 144hz. (Before I had set it at 60 fps)

If anyone hasn't guessed it by now, the problem is that it caps at 60 fps for no reason. The moment I changed from borderless windows to fullscreen, that fps cap goes from 60 to 144. And vice versa. No idea why, checked my nvidia settings for ff14. I set the preferred refresh rate to highest available, no change. So changed it back to application controlled.
Vertical sync is currently at "use the 3D application settings". I had switched that to off/on/adaptive. As always no changes to fps.
Settings is currently set at ultra with everything at max. I've lowered it to low and yet again, no changes.

The monitor I am using a BenQ XL2411Z, this monitor is 144hz monitor. I do have a second monitor which only goes up to 60hz.

Windows 10 64-bit Home
CPU: i7 4790k 4.0ghz
GPU: EVGA Geforce 1080 FTW
RAM: G.skillz 2x8gb 1866mhz
Game running DX11

As far as I am seeing there shouldn't be a bottleneck at all. No explanation on why its capping at 60 fps.
Sometimes it gets stuck at 60fps, sometimes it caps to 144fps as intended.

If there were such a bottleneck, fps should be struggling to get to 144, why would it just be stuck at 60?
Any assist would be appreciated.