Moving in certain ways an item that is repeatedly given by a command block makes the slot appear empty

Steps to reproduce :

1) If you're not in a random world, make sure the FIFTH slot (not the fourth, the fifth !) of your hotbar is empty, as well as at least one slot of your inventory

2) /gamerule commandBlockOutput false (only avoids flooding chat)

3) /give @p minecraft:repeating_command_block

4) Place the command block and click on "Needs Redstone" so that it switches to "Always Active"

5) Put this command in the command block : /replaceitem entity @a hotbar.4 minecraft:redstone

6) Click "Done"

7) Now, do one of the following actions (list may be incomplete) :

– Shift-click

– Click then drop out of the inventory

– Click then drop on the "Destroy Item" tile (creative mode)

8) The item is back, but after performing again one of the above actions, the slot will look empty, and trying to perform one of these actions yet another time won't bring the item back again. The only things that will work are :

– Using the "drop" key while the inventory is closed (so works only if the item is placed in the hotbar)

– Placing any item where the redstone should be (but that item will be lost)

Other things that might be helpful to know :

– Closing and opening the inventory BEFORE performing a second action will prevent the bug from happening

– If the command block places in that slot a stack of at least 2 items, by right-clicking it (instead of left-clicking), the bug will still happen but since there will be at worst (as long as only right-clicking) half of the original stack. Meaning that the third action is possible, and will provide the update needed to make things "normal" again.

– If thrown (by dragging the item out of the inventory) and then retrieved while the inventory is opened (even if it means closing it, moving and then opening it again), it will go back in the right slot (unlike the shift-click), but it will already be in the "bugged state" (i.e. performing only once one of the actions I listed will be enough to make the slot empty again)