All registered custom blocks in the creative menu fail to load with the following issue.

[Blocks][error]-block_definitions | C:/Users/%USER%/AppData/Local/Packages/Microsoft.MinecraftUWP_8wekyb3d8bbwe/LocalState/games/com.mojang/minecraftWorlds/NM5DXvP4AAA=/behavior_packs/FC_B | blocks/block_acacia.json | description | register_to_creative_menu | child 'register_to_creative_menu' not valid here.

[Blocks][error]-block_definitions | C:/Users/%USER%/AppData/Local/Packages/Microsoft.MinecraftUWP_8wekyb3d8bbwe/LocalState/games/com.mojang/minecraftWorlds/NM5DXvP4AAA=/behavior_packs/FC_B | blocks/block_acacia.json | Failed to verify block

We've attached the block file from this add-on, and I've found a workaround to keep it running till it's fixed.

The blocks will load and work properly if the property "register_to_creative_menu" is removed from the description. (They will not be available in the creative menu, but they will be available for /give commands and everything else.)

We hope this is rectified fast because it makes testing custom blocks much more difficult.