It seems that some items may be replaced. For example, when I was wearing an elytra, and then I quickly switched to a chestplate, my original elytra was saved, but there seemed to pop out another elytra in my inventory, and my chestplate had disappeared.
MC-267909
The bug existed on a singleplayer world
Resolved
Awaiting Response
0
Please provide a video of the issue occuring, with consistent and reliable steps to reproduce it. Having the F3 menu open would also be helpful with the video. 🙂