Hostile mobs spawning in Mooshroom biome

Im using a Samsung Galaxy S7 running Android 7.0 and normally I just get spiders spawning on leaf blocks when planting trees in a mooshroom biome but this time after a thunderstorm I had skeleton horse spawn and there are no non mycelium blocks for mobs to spawn on in the surrounding ocean biomes. This is undoubtedly a bug since the only hostile mobs that can spawn in a mooshroom biome are suppose to come from Spawner cages alone