Mushroom Biome not generating

I attempted to try a seed of a Mushroom biome in my Mimecraft. First seed is pot22: I spawned on an island next to a mushroom biome. Well, I can't see a mushroom biome, and the chunks on a suspected area where the mushroom biome in not generating. Second seed is 1417267005 : I tapped "Generate World". Then suddenly, the loading bar freezes about 1/3. So I suspected that this is a bug. Please fix. I hope this helps.