Saved hotbars should stay on the world/server that the player is logged into. The way it is, allows players to create modified items in singleplayer mode, then save the hotbar and load it on my creative server.
This creates lots of trouble since players can create their own command block in singleplayer, then load it on my server and place a button on it and run any command as my server.
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However, this issue has been resolved as a Duplicate of MC-114692.
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