Slate is covered by missing texture in Education Edition

This issue is about chalkboards as a placed block, not how to obtain chalkboards.

Can confirm. Relates to MCPE-187696

Steps to reproduce:

1. Create a world with cheats enabled and turn on the "Education edition" toggle.

2. Join the world and give yourself a "slate".

3. Place the slate.

Observed results:
The slate block will render as a "?".

Expected results:
The block should render properly.

I Could confirm with Android 

Confirmed in 1.21.50.28 Preview. Had to now be caused by MCPE-188223.

This issue has been resolved as Won't Fix.

The Slate item was never intended to be available in the game when the Education Edition toggle is off. That it was present in creative inventory was a bug (see MCPE-187696), and it was fixed in 1.21.50.28 Preview/Beta. Since the item is not part of the game (with the toggle off), its texture is absent from the game (with the toggle off), which is why it's shown as the "missing" texture.

"Fixing" this issue would involve either making the item (including its texture) available again, which is contrary to design, or deleting any instances of blocks and/or inventory items of that type, which is something Mojang never does (there's a policy against ever intentionally deleting something a player built). In contrast, making the item unavailable only causes its blocks to become inert and harmless, so it's safe to leave them or leave it to the player to get rid of them.