Not sure what specific setting is causing this, I've experience this issue with LibreOffice 5.2, 5.3 and 6.0, menus don't populate, and I can't resize the image.
This issues doesn't occur if I use the main display of my laptop screen, only on either of the 2 additional screens connected via the display link (Dell d3100).
Tried swapping usb ports, hdmi/dvi cables/adapters.
The issue doesn't occur if I use hdmi without the DisplayLink, so the DisplayLink seems to be the culprit. Screenshots attached. First is LibreOffice 6 functioning normally in my laptop display, second is the file menu not populating, 3rd is the window not resizing.
I actually can't get LibreOffice responsive at all if I drag it to another screen using the DisplayLink.