Steps to reproduce...
1. Start with a clean install of Newscoop 4.3.1, no sample data
2. Create a publication/issue/section and a simple Article Type.
3. In the Article List for the section, create a new article.
4. Click Media -> Images -> Attach and upload any PNG or JPG image.
5. Go through the steps of the image wizard and click Finish.
6. The article edit screen is now a blank page. The rest of the admin interface works OK. The Media Archive shows that the image was uploaded.