The way equipment is currently listed in most output sheets and previews can cause items to vanish in certain circumstances. If you have two instances of the same container item, and each of these holds some of the same item, part of these items are not considered for the output.
For example, create any new character and by 2 of "Pouch (Belt)" and 2 of "Potion of Cure Light Wounds". Now equip just one pouch and then put just one potion inside the pouch. Then equip the second pouch, which will be listed with its own entry now in the equipped inventory panel, and then put the second potion into that pouch. If you look at an output sheet or preview now, you will see both pouches listed individually, but only one of the potions is listed, when there should be two entries, or at least one entry showing 2 potions.