There is a similar issue raised on AskUbuntu: it appears that libreoffice-gnome is not automatically installed. You can install it from the command line, or get it from Synaptic (which is what I did:
Note that in the screenshot, libreoffice-gtk and libreoffice-gtk2 are also shown as installed: when you mark libreoffice-gnome, the two "gtk" packages get automatically marked as well. Since installing, my file operations on LibO 5.2 have gone back to "normal" for me (was getting a terrible interface before).