Why doesn't Skip Forward and Fast Forward work on the Xfinity App on ROKU?

The ROKU standard is to display a screen when Fast Forward or Rewind is in use, the Xfinity app just shows a blank screen making you "guess" when to stop. The Right and Left buttons are traditionally a "Skip forward", "Skip backward" by some quanta (30 seconds, 1 min) - instead Xfinity have implemented these as alternative FF and REW. Why?

Is there any way to get the Xfinity App to work properly on a ROKU device?