Strange, never happend to me...
Did you assign your inventory to the character?
Have you created slots in the inventory with object areas and set as placeholders for items?
are you using the builtin "dragging" solution where the cursor changes to the current held item?Could it be that you set an item and your mouse position is at the top-left position?
Have you checked to see if you accidentally created any loose polygon points? A lot of people create them by accident - I've done it myself on the odd occasion myself; but with way system instead.Checked.
do you have accidently have a second inventory interface with one item place holder slot and when adding an item it scrolls to the last added by default?Thanks sebastian, that was the key!its the only way i could think of that would make an item appear there..