Version: 5.1.6.2
Build ID: 1:5.1.6~rc2-0ubuntu1~xenial10
CPU Threads: 4; OS Version: Linux 4.9; UI Render: default;
Locale: en-US (en_US.UTF-8); Calc: group
None of the Base reports open. I get for example: “The Document ‘Cultivation’ could not be opened.”
Do you really use such an old system? Kernel of Linux isn’t supported since over a year.
Also LibreOffice 5.1.6.2 has been published 2016-10-27.
Might be you didn’t install all packages for report builder. Special Ubuntu won’t install this packages by default, and Build ID of your version shows: You have installed the packages from Ubuntu, not original packages form LibreOffice.
Don’t know if you get this packages anywhere, because also this version from Ubuntu wouldn’t be supported any more.
sudo apt-get install libreoffice-base
sudo apt-get install default-jre