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Sorry @petit3xxx from your original post I thought you were having trouble with Candy Royale and not the Win Streak.
What level are you on? The only thing I know that can make your Candy Necklace disappear are the levels that do not allow you to use boosters.
If the pre-game booster (Colour Bomb, Striped/Wrapped, Fish) holders are empty at the start of a level then your Win Streak temporarily disappears.