Updated to Preview 1.21.50.28
Create a new world in creation
Make sure Education Edition is turned on
Create a world and join it
Open Inventory
Click on the button in the third category (the one with the icon of a bed)
Scroll down until you can't find it.
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Comments 5
migrated
In other words, no matter what it is bug or suggestion. Slate as Education Edition item will never add the Regular Bedrock Edition. So This issue can solved as invalid or work as intended.
The slate/any other chalkboards are unobtainable blocks that cannot be given via the use of commands or by enabling the "education edition" toggle, thus they only exist as an actual block/item in the Education Edition version of the game. Despite all this, chalkboards still exist as entities within the game files.
The fix for MCPE-187696 made slates unobtainable in the base game once again, which is intentional behavior.