I have Libreoffice 5.3.0.3 installed on a windows 10 x64 machine and navigating through cells is not possible. On hitting one arrow key the whole spreadsheet moves instead that only the highlighted cell moves. On a Windows 7 x64 machine everything works fine. I tried to reinstall this version but the failure did not leave.
Have you tried to toggle with the 'Scroll Lock - key'. It has similar function as you describe.
I installed 5.3.1.1 and with this version it works fine. But you are right, enabling Scroll Lock keys describe exact the behaviour and i think this was the culprit.