This is intentional, Mojang has previously stated that items that can't be obtained in survival don't appear in the creative inventory to avoid confusion from new players
These items haven't been properly added yet. They will be introduced in a future update. For now they're only accessible using commands, until they're finalized.
This is intentional, Mojang has previously stated that items that can't be obtained in survival don't appear in the creative inventory to avoid confusion from new players