When renaming a block in an anvil and then placing it, the given name changes back to the default form.
For example: place a lever in the anvil and rename it bob, after that place the lever in survival mode and break it again, the lever is now called Lever again. this goes for every block( tested a round a dozen)
Thank you for your report!
We're actually already tracking this issue under MCPE-25845 so I've requested this report be resolved and linked as a duplicate.
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