I watch sports slightly delayed in order to skip time outs, inning breaks, halftime, etc. too.
Cloud DVR can be affected by a weak signal. It's possible that a signal issue during fast forward could be causing playback to revert to the beginning. Another consideration is how close you are to the end of recorded programming. Even a local DVR can be affected when playback gets close to 'live'. You could also try fast forward at a slower speed to see if that makes a difference.
As a workaround, make the channel the sports event is on the current channel. When you get to within a half hour of live, abandon the recording and reverse the live buffer to where you were. Before doing that, be sure to mute sound and hold your hand in front of the TV to avoid a spoiler.
