Orcs are not appearing in the plains biomes.

I tried increasing the spawn weight from 10 to 50 and they still don't spawn.

The only biome mod I'm using is William Wythers' Overhauled Overworld

Might be fixed with the latest update :)

If the biome mod you are using is just adding biomes via a datapack, only vanilla biomes will spawn adventurez mobs btw