since the comment above is a little vague, here's a better explanation:
in the "generation" tab of your block, select the biome you want your ore to generate in. for the sake of this explanation, let's use a redwood forest and sapphire ore.
when you get to the generate tab, configure sapphire ores' no. ores per chunk and no. blocks per ore, and then select the redwood forest for it to generate in.
then in your dimension, select redwood forest as one of the biomes it can generate.
and voila! test it out by replacing the main ground block with air via commands, I.E. /fill ~-64 ~-64 ~-64 ~64 ~64 ~64 minecraft:air replace minecraft:stone . obviously replace stone with your main underground block, but it SHOULD generate your ore. if it doesn't, then your Mcreator is bugged and broken.
Select biomes that you have in your dimension for generation biomes
since the comment above is a little vague, here's a better explanation:
in the "generation" tab of your block, select the biome you want your ore to generate in. for the sake of this explanation, let's use a redwood forest and sapphire ore.
when you get to the generate tab, configure sapphire ores' no. ores per chunk and no. blocks per ore, and then select the redwood forest for it to generate in.
then in your dimension, select redwood forest as one of the biomes it can generate.
and voila! test it out by replacing the main ground block with air via commands, I.E. /fill ~-64 ~-64 ~-64 ~64 ~64 ~64 minecraft:air replace minecraft:stone . obviously replace stone with your main underground block, but it SHOULD generate your ore. if it doesn't, then your Mcreator is bugged and broken.