Comp games not promoting

Three times I have stayed in the rank of Gold 4.

One placement of 11 losses and 7 wins made my rank stay on Gold 4 which I expected.

Another set of games being 7 wins and 6 losses didnt rank me up.

Then the third set of games of 7 wins and 5 losses didnt rank me up either? This is truly annoying and I dont feel like there is any point playing competitive anymore since the game is refusing to promote me? Not in a single game did I under perform or do badly. I either was the best support of both teams or just average.

Common issue or just me?