I created an falling block at first.
Then I use the command:
/data modify entity <the uuid of this block> BlockState.Name set value "minecraft:grass_block"
But the the appearance of the falling block was not changed.
If I use this command:
/data get entity <the uuid of the block> BlockState.Name
The command returned "minecraft:grass_block"
Thank you for your report!
We're tracking this issue in MC-72849, so this ticket is being resolved and linked as a duplicate.
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