When using blockstates that are not supposed to be held by the player the block just shows as air in the customisation menu, for example:
When using "3;minecraft:bedrock,2*minecraft:stone:2,minecraft:grass;1" everything works fine and Polished Granite is shown and named properly, however, when using: "3;minecraft:bedrock,minecraft:water,minecraft:farmland,minecraft:wheat:7;1;" wheat is named air and displayed as an air block (actual world generation works fine however).