In an Unity UI Inventory, Appear Type = Manual, Show Active FX when cursor hovers over Item checked, when you pick up a item - which has Main Graphic and Active Graphic set - when you right-click or left-click to release the item in its slot it stays with the Active Graphic icon rather than Main Graphic..
If instead you click with an item on another without Interaction, the item returns to its place with the correct icon Main Graphic but the item clicked remains in Active Graphic.
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Please also keep separate issues in separate threads - re-post your final question in a new thread with a screenshot to illustrate.