Here is what I mean by "upside-down corner stairs": https://i.imgur.com/viiDkAa.png

When I get some information from an upside-down corner stair with block.getBlockData().getAsString(), it correctly says "half=top."

When I do ((org.bukkit.material.Stairs)block.getState().getData()).isInverted(), it incorrectly gives false.

Here's an image where I sent messages to my player with information about an upside-down corner stairs block. Notice "half=top" and "inverted = false." Inverted should be true since the corner stairs was upside-down. https://i.imgur.com/ByQvpOm.png