When making changes to the draggable items, the preview of the dropzone is not updated.
It looks like the JS is trying to target some non-existent IDs.

Affects both Boost, and Clean so I don't think that this is a recent regression.

1. Create a new Drag and drop onto image question
2. Set a background image
   1. Note how it doesn't show immediately
3. Set some draggable areas
   1. Note how it doesn't show immediately
4. Save changes and continue editing
5. Update the text in the draggable areas
   1. Note how it doesn't show immediately