Null controllers disappear

Hi,

I've build a 2D animation rig using DUIK. I have null object controllers for the hands, feet, chest and hips. I also have these controllers parented to an overarching sky and ground controller (yellow null objects). The puppet works brilliantly most of the time, however lately when I open the rig, the yellow null object controllers are gone and I can no longer select and move anything with my mouse. I have increase or decrease position coordinates to move my puppet.

Please help me. It's absolutely infuriating. Is there a setting I have somehow switched off to loose that functionality?

Cheers

Tara