Forge log link :https://www.dropbox.com/s/1tlaxqgc5ym6s3k/latest.log?dl=0 i dont think this will help but here you go.
Problem: with EvilCraft-1.11.2-0.10.26 and CyclopsCore-1.11.2-0.10.4 mobs are over spawning in the overworld and mobs in the nether like blaze and wither skeleton are not spawning but with CyclopsCore-1.11.2-0.10.3 and EvilCraft-1.11.2-0.10.25 it seems to work fine.
Expected behaviour: for mobs to spawn as normal
Steps to reproduce the problem: not sure on this it seems to happen in my modpack The New Frontier but not in vannla but like i said when i downgraded it it works fine so it could be something with EvilCraft and other mods.

Can you reproduce this with just EC and CC installed?
Nothing much has changed between version 25 and 26, so EC is unlikely to be the cause of this.

hopefully you can find out why this happens if not ill have to stay with older EvilCraft in my pack

may have been a false flag back to the drawing board for me.