[Client] Getting into my series caused me to have a loss

I played 4 ranked games on February 11th. I won all 4. The 3rd game put me into my series with ZERO wins or losses. However, when I won the next game it game me both a win and a loss. Even if you were to check my match history you would see that my last ranked game loss was 5 ranked games ago which would make it impossible for me to have a loss in my series.