Variations of tallgrass and ferns do not correctly display textures

when creating variations for tallgrass, double tallgrass, fern, and double fern textures large areas of land will not have grass textures applied to them and instead will show as invisible in 1.16.200 and the biome grass color in 1.16.100.

to reproduce: activate a pack with variations for grass/ferns, go on a server, look around until you find grass/ferns that are completely invisible instead of a normal fern/grass texture

observed results: a completely invisible grass/fern block

expected results: grass/ferns with the corresponding variation of texture applied to them