When flying an elytra, if you keep flying, sometimes chunks don't load and you hit an invisible wall, take damage and fall out of the sky.
Sometimes when flying, all of the chunks go invisible (but you can still fly) and you can only see entities.The chunks don't reappear for a while.
Thank you for your report!
We're actually already tracking this issue at MCPE-55671, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
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