Can't Open Drum Kit Designer when Producer Kit Selected

I can't open the drum kit designer after I've selected a producer kit (e.g., SoCal+).

The Drum Kit plug in disappears after selecting a producer kit, and can only be opened with a normal (non producer) kit selected. With the Drum Kit Designer window open, I can change to a producer kit, and then edit, but once that window is closed I can't find a way of opening it again.

This means that if I want to edit a producer kit further, I can't. I have to go back to the normal kits, and then lose the changes I'd made before.

Is there a way around this? Am I missing something?