I've just tested this by piling a bunch of headgear, armour, shields, footwear and melee weapons together, and I can use '+' and '-' to scroll up and down the list of items (it spans more than a single page), and everything is listed fine.

The obvious difference is that I don't have any potions in the mix.

When I then add a potion to that same pile, I scroll to the bottom of the list, and as Baranor reported only the heading for Potions is visible, the potion itself is not in the list.

And as expected, once I pick up just enough items for everything remaining in the pile (including the potion) to fit on a single page, the potion is listed at the bottom.

I tried it again with weapons and it did happen again for me. It may not happen with all types of items.

The behaviour seems to be consistent when equipping across all items. Try this when there are more items than fit on a page which can be put in the right (or left) hand slot.
With the hand empty try 'equipping' it and scroll to the bottom (note the last item).
Then just 'V'iew all the items there is invariably an extra one.

Fixed for JADE 0.1.3. Happens in all item list displays under special circumstances.