Crafting Dead Origins. Zombies don't spawn but normal mobs do. ;(

So I have a problem with the mob spawning in my Crafting Dead Origins Server. I love using aternos for hosting my servers and it works well for the most part. Sometimes a few glitches here and there but that's inevitable.

When I start my Crafting Dead server I log in like normal and the world doesn't spawn CD Zombies, doesn't have the biomes, and does NOT have the structures. So is there any way I can do to fix this problem?

Thank you and have a great day everyone!

Also is there a way to do this with a map?

I do not believe that it is the modpack its self.

The reason why is because the modpack works correctly for my friend. I used to be able to fix this issue until the aternos website change. (GUI change of server)

... wtf do you mean by "reinstall" my server....