I have two keyboard layouts installed in my system. When I use US keyboard layout, arrow-keys control cell selection. When I switch to the RU layout (Alt+Shift), arrow-keys control scroll-bars.
LibreOffice 5.3.4.2
Debian 9
Awesome-wm 4.0
Please try resetting the user profile, sometimes solves strange issues.
https://wiki.documentfoundation.org/UserProfile
Usually it’s enough renaming/deleting the file “user/registrymodifications.xcu”, it affects all the options in Menu/Tools/Options, and the files “user/basic/dialog.xlc” and “scrip.xlc” are overwritten, additionally custom colors in “user/config/standard.soc” are lost.