I had a traces of anciant kartia's labyrinth on me, went in k95 solo (normal one not the new one) and the traces got deleted from my inventory.
We've seen reports of this and the QA team is looking into it; they'll submit a bug report as necessary. Please contact the support team (http://www.lineage2.com/en/game/the-library/items/appearance-stones.php) to report that this happened to you, though, for further support. (Include server name and character name.)