Same as https://bugs.mojang.com/browse/MCPE-48406 but that seems to be ignored as it references 1.12 not 1.13. The bug is still there, maps can't be loaded or created, the game is unusable.
Related issues
duplicates
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I've updated the affected versions to 1.13.1
Can confirm this bug is still there on 1.13.1. The game is still unusable.