Thanks for the suggestion. 
Yes, this is with a DevPack development (my Alloy replacement Blog). I have done numerous restarts as it has been like this for weeks. Initially you could see nodes dropped in the dropzone but once they disappeared they never come back. Even clearing everything out of the dropzone and re-adding doesn’t show anything.
The only way I can edit the structure of contents in the dropzone, is to select the Component at the top of the breadcrumb (Container A) in the image and cut and paste it into an area outside of the dropzone, edit it and then paste it back in. I can only easily select Components in the dropzone by selecting Components in the breadcrumb. This is a workaround in development but would be unusable as a published component. 