It is a bit finicky in its current state. We are actually working on a redesign at the moment. When you edit text, it should function fairly simply, but dragging blocks in might take saving it and refreshing the page. One trick I have been told is to try and make the editor not appear over the blocks.
There are also a few tricks in the actual editor as at the top of the note, you can pick what actor it goes to and top left you can also adjust the blocks to being draggable or just a picture.