Jimi

It also doesn’t work when modifying the entity data by using this command (assuming the block is placed at 0/0/0)

/data modify block 0 0 0 "align_items_to_bottom" set value 1

when you do

/data get block 0 0 0

afterwards it correctly says that the property is set to true.
Also if you close and reopen the world, and then redo the /data get command, it still says that the property is true, but the rendering still shows items in the middle of the Shelf