Versions
WorldEdit version: 7.2.1
Platform version: Bukkit 1.16.4

Describe the bug
//Setbiome command does not change every block in a given chunk, leaving some blocks such in original state.

To Reproduce

1. use //wand to select a large given area
2. use //setbiome to a different biome

Expected behavior
All grass blocks would change into a uniform color

Screenshots

Additional context

Are you only selecting the surface? https://worldedit.enginehub.org/en/latest/usage/regions/regionops/#setting-biomes

Yes. //expand vert fixed it

Thank you!