After updating to 1.14.0 on the Nintendo Switch, Chunks of the world where I had built reset to how they were before anything had been built. Portions of player made villages dissappeared and turned to sunflower fields, a mountain i had built extensivly in filled itself back in, and the Facade to a large build i did was sheered off. This did not all happen immediatly, but some time after filling in a new map. I was able to recover my builds by reloading a rehlm save from 8 hours earlier but am afraid to play anymore as I dont want my builds to vanish and to have to lose another 8 hours of work.
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Sounds like this one, https://bugs.mojang.com/browse/MCPE-58514