The jellies are located on the peninsulas on the bottom of the board, making them very hard to clear, especially on the left and right side of the board, where making vertical striped candies to clear lots of them in one go is very hard (and nearly impossible on the extreme left and right side of the board).
Additionally, liquorice swirls ensure that the player needs to blast one area three times, which can be a real nuisance when most jellies on the left and right side are very hard to reach.
Finally, icing prevents the player from clearing jellies with matches at the beginning of the game.
In iOS and Android versions, the liquorice swirls are not absorbed by the striped candy + wrapped candy combination, making it impossible to boost your progress should the player be lucky to get vertical striped candies on the centre of the board.
The jellies are worth 42,000 points. Hence, an additional 3,000 points is required to earn one star.