Another issue with Libreoffice 5.2 on Debian is that sometimes images are not displayed within a document. They are there, but are replaced with what appears to be a placeholder.
To fix this goto Tools menu and select Options. Then go to Libreoffice-Writer -> View
From here make sure that Images and Objects is selected under Display.
Hopefully this will solve the issue.
This work is licensed under a Creative Commons Attribution 4.0 International License.