this is what i have so far, character can go left and right just fine inside the object but not up and down 
Check your character movement component for swimming. You want to look into it. When I first started messing with unreal 4, I didn’t check the movement component for flying and I ended up with this.
You might have to enable flying too?
And this… It worked…but there was clearly an easier solution, lol.
That was my very first BP.
Adding moveinput z should work. Shouldn’t need to set movemode to swimming like that either. If the movement comp alllows swimming, it should auto swim when you overlap a physics volume which is set to water.