When placing any container down in 1.13 then downgrade to 1.12.2 the container will disappear.
Same with tamed horses and donkeys.
PS: in my testing, downgrading from 1.13 to 1.12.2 a tree also moved to a different spot.
MC-130780
Containers, tamed horses and donkeys disappear when downgrading to 1.12.2
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Downgrading is not supported, and in fact will completely reset the world if I recall correctly.