I just started a new world with the Dalek mod and a couple other mods, there don't seem to be any hostile mobs spawning. I can spawn them in with items, or spawners in the world will spawn them in. Other than that none. 

My mods are:

-Dalek Mod update 50.1

-Bibliocraft

-BiomesOplenty

-Chisel

-Inventory Tweaks

-Iron Chest

-JEI

-Journeymap

-Mousetweaks

-Naturalnetherportals

-Pirates

-Rex's additional Structures

-Ruins

-Twilight Forest

Any help is appreciated

Do you have the difficulty set on easy, normal or hard?

They do spawn just takes a while 

It's on Normal, and I have been playing the world for a few hours. I've had passive mobs like polar bears, llamas, pigs and cows all spawn normally.

Did you check the configs file

# Configuration file

general {

    "client side" {

        B:"Custom Title Screen"=true

        B:"Panel names"=true

        B:"Show Sky boxes"=false

        # Min: -2147483648

        # Max: 2147483647

        I:"Sky box levels"=32

        B:"Sonic Shade commands"=true

        B:magic=false

    }

    "server side" {

        B:"Acid Rain"=true

        B:"Air loss"=true

        B:"Drop Tardis Item"=true

        B:Nitro-9=true

        B:"Sonic Blaster"=true

        B:"Sonic Griefing"=false

        B:"Spawn Daleks"=true

        B:"Tardis Boundary Generation"=false

        B:"Unlock all locked items"=false

    }

    tardis {

        # Min: 0

        # Max: 2147483647

        I:"Limit Tardis Count"=1

        B:"Limit Tardis Player"=false

    }

    mobs {

        B:"Classic Player Griefing"=true

        B:"Cybermat griefing"=true

        B:"SWD Daleks grief"=true

        B:"Suicide Dalek Exploding"=true

        B:"Weeping Angels grief"=true

        B:"Weeping Angels teleporting player"=true

    }

    debug {

        B:"Extended mod log output"=false

    }

    "dimension ids" {

        I:"Cave Game ID"=56

        I:"Classic Dimension ID"=55

        I:"Gallifrey ID"=59

        I:"Moon ID"=54

        I:"Skaro ID"=53

        I:"TARDIS Dimension ID"=52

        I:"Trenzalore ID"=57

        I:"Varos ID"=58

    }

    regeneration {

        # Explosions on regeneration?

        B:Explosions=true

        # Toggle the POV changing on regeneration

        B:"Toggle Player FOV Change"=true

        # Toggle your point of view changing during Regeneration

        B:"Toggle Player Perspective"=true

    }

}

This is the Dalek mod config

I know him not a dev or John but shouldnt there be an option to configure mob spawns 

I tried to reinstall, nothing changed in the config file.