They must have found the cause of the issue. I tested it again, it's working on windows 10 as well. FF, rw, pause, play all work from an mce remote.
When pause is pressed, the requested function occurs, the control bar appears at the bottom of the screen, the 'trick play' box shows up near the top left of the screen and the TV slice appears. After a few seconds only the trick play box disappears (not sure why the slice had to appear and stay on the screen while paused - it takes up a lot of the paused screen's real estate). If I press exit, it removes both and stays paused.
There is different behavior when using MCE ff, rew vs the HD ff, rew (left, right arrow) commands. HD only brings up the control bar, mce remote brings up both the control bar and the trick play box. Not sure of that's intended behavior or not. In both cases, as would be expected, the controls dissapear after a few seconds.
Unfortunately I also discovered that mce channel change function is not work this morning, and neither does changing channels by opening discover, selecting a show and clicking on watch. No channel change occurs. Using the slice to change channels still works though.