Hi there,
I know this is an old post, but I thought I would respond in case anyone else runs into this problem. I had a similar issue just a couple of weeks ago: even though I mirrored both the character and the item, when mirrored, the item's image flipped but was still in the same location in relation to the player (as it was pinned in place) and sort of floated behind her. If the item is a weapon for example, you can imagine how that could be problematic. Perhaps this is a rookie move, but I fixed it by moving the image point on the pinned item so that, when pinned, the image point falls in the centre of the character. It now mirrors properly: when the character and the item are mirrored, the item (ex: weapon) appears on the correct side of the character, rather than appearing to float and trail behind her.