Hi! I disabled generation of anything other than climate for worlds with imported heightmaps in version 0.3. Sorry for the letdown :<
It's pending some decisions on how to handle missing data and backwards compatibility.
Long story short, to generate biomes, we dont need only need elevation and climate, we also need bedrocks, soil texture, soil depth, soil richness, and so on. Gleba currently doesnt support generating those in a way consistent with the heightmap due to how difficult the task would be. I have some plans for a proper world editor thatd make making this missing data feasible but it's not available yet.