Windows 10 Store Games

[1GoldGunFTW]

Gears of War UE and Forza Apex :  Whenever I set the graphic options to Vsync ON , Dxtory will record ,  but when I set the fps to uncapped or my monitors refresh rate it will not.  So my question is why will Dxtory record these games when Vsync is on and will not when its off?