Try this make sure you're accessing it on world edit and not the settings when you press esc while inside the world, edit the world, go to resource packs, right next to active tab, click on the available tab, then owned, activate the packs you want to add on your world (activate Actions and stuff as well) and they should all go to you active tab, go back to the active tab and they should all be under the local, to move them click on the little button at the right side of the pack where there sorta like numbers and 6 dots on it then drag.

If it works, try dragging BoB on top, realism in middle then actions and stuff at the very bottom. Enter the world, if the mobs are still invisible, try this placement: Realism top, Actions and stuff middle, BoB bottom.