Mushroom Islands sometimes aren't generating terrain above water

Mushroom islands sometimes do not generate any terrain above water, as shown in the screenshot that doesn't appear to have a mushroom island pictured. However, it shows up as the mushroom_fields biome in the color of the water and debug screen.

The size also varies wildly, however I don't think that part is a bug.

 

Seed: -4949127125411102598

And the coordinates are all shown in the screenshots