Missing Inventory
Recently, I logged in with my character Aidan Eroth and found that my character was missing two packs containing various types of equipment. The most notable from memory was Nymawyn’s Corellon ring and an Underdark Spear that is specifically designed for attacks against oozes. I was carrying these packs through a couple server resets so far, so I thought it to be quite strange.
Domare
I can assure you that this does happen. I've lost a few things myself and always forget to report it because they're typically in a strange inventory page or something. I'll try and keep track and report it asap.
Items carried in bags can be lost for a variety of reasons. The main one I know of being different shapes.
When you get subdued/killed the items in a bag vanish and are placed back inside the bag in that instance. If an item doesn't fit in the bag its lost forever. Even though you have the items set up perfectly the ai placing the items into the bag does it clumsly and in a random order.
The only solution is to only keep items of the same shape together in bags. (Though I find it rather safe to keep 1x and 2x together)
Oh and always try to leave a few slots in the bag!