When a mine cart with a hopper is just moving around on rails, it will just randomly disappear and you will have to make another one. This might also being affecting all types of mine carts.
How to make this happen:
1. Get a mine cart with hopper
2. place the mine cart on rail that goes in a loop
3. wait for it to disappear.
It should stay there and not despawn
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We're tracking this issue in MCPE-21416, so this ticket is being resolved and linked as a duplicate.
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