Not bug, but

[TecnoBacon]

In landscape you have all calls based on the index except the enable chunk, it is xy based. It would be better if there is a chunk enable by index, this would keep everything coherent as any well made app will already maintain a matrix of chunks that holds the TV index value. Unfortunately the matrix may not match TV xy matrix for landscapes.

Eric

[SylvainTV]

OK indeed that's not logical in this case. I might change it
But some other functions are also using XZ, such as ExpandTexture etc.. What to do with them?
And using the index is nice because it allows you to use -1 to batch the operation on all the chunks

[Mithrandir]

Maybe you could just overload them implementing both options?