Undecided match

I played a match today and my opponent “paused” the game (when he started to lose) and I had to throw him out to finish the game.
In the past in situation like this I have always won such match, but this time the result is marked as “Undecided” and my mmr has not changed. I will add that this is my only case when the match is “Undecided”.
Does anyone know why this happened and how I can avoid this in the future?
Is there a chance to verify this match and correct the result?
I know from my experience that many players who are losing the match end such game by pause it. In such cases marking the match as “Undecided” is very harmful to players who should win.

29.08.2019 Update - The result is still “Undecided”.
30.08.2019 Update - The result is still “Undecided”.