Reserved item spaces are not being saved between sessions.
When you put something in your inventory, then to your hand, and log out with it IN your hand, that slot will not be "reserved" for that item when you log back in.
Why is it an issue?
Some people log out with a gun/mele in their hands so they are ready when they return to play.
When they return, that gun/mele will no longer have a reserved space in their inventory. If the inventory is quite full, or only has limited single/double spaced slots left to fill, picking a single space item could be placed into the previous space for the gun/mele, not allowing you to "quick bar" the gun away for, say, a bandage/meds.