Promo reset

I had been grinding ranked recently and eventually reached the promos from Silver 2 to Silver 1. I had lost the first game then barely won the second and easily won the third. Keeping this is mind I should be in Silver One right? Well after the third promo game, I saw on the top of the screen that it said I qualified for the exact same promos that I got through. I had lost through the second time and was so frustrated I wanted to break through in one go but ended up losing 3 games in a row and getting kicked down to Silver 2 with 40 LP. Is this thing like a bug or something?