Any simple calculation using '+' '-' '/' or '*' gives me 'No pivot table found at this position.' followed by '508' or '509' depending on how I format the entry. LibreOffice 5.1.2

[Manticore]

Examples: =(C4/A4), =(C4A4), =(C4+A4), =(C4-A4) give ‘No pivot table found at this position.508’
=C4/A4, =C4A4, =C4+A4, =C4-A4 give ‘No pivot table found at this position.509’
I have never even heard of Pivot Tables until this problem occurred.

Just noticed - the status bar at the bottom gives ‘Error: Invalid semicolon’

It’s all just become a whole lot more complicated. I tried a different Window Manager (Enlightenment rather than my usual XFCE) & the problem disappeared. Hey Ho! Taking it over to the XFCE forums.

[erAck]

That rather indicates that within Enlightenment the en-US locale is used for UI, and in XFCE you have another UI language/locale set you usually work with and for that a non-matching LibreOffice language pack has been installed.

[Manticore]

After trying a couple of other Window Managers + running LibreOffice straight in X with no WM - all of which gave me the same problem.
:
*** I Solved It! ***

Not XFCE.
Not LibreOffice.
I normally set the system RC-LANG to en_GB.UTF-8 and RC-LC-TYPE to en_GB.ISO-8859-1. Some recent update has removed the RC-LC-TYPE setting. For some reason Enlightenment overrides this while other WMs including XFCE do not. Seems like LibreOffice does not like UTF-8

[erAck]

LibreOffice is perfectly fine with UTF-8

[erAck]

Likely the version of your installed LibreOffice language pack does not match the installed LibreOffice program version. They MUST be of the very same release version.

[Manticore]

I’ve got:
libreoffice-writer-5.1.3.1-1.5.i586
libreoffice-calc-extensions-5.1.3.1-1.5.i586
libreoffice-writer-extensions-5.1.3.1-1.5.i586
libreoffice-base-5.1.3.1-1.5.i586
libreoffice-mailmerge-5.1.3.1-1.5.i586
libreoffice-filters-optional-5.1.3.1-1.5.i586
libreoffice-calc-5.1.3.1-1.5.i586
libreoffice-math-5.1.3.1-1.5.i586
libreoffice-5.1.3.1-1.5.i586
libreoffice-draw-5.1.3.1-1.5.i586
libreoffice-pyuno-5.1.3.1-1.5.i586
libreoffice-impress-5.1.3.1-1.5.i586
libreoffice-l10n-en-5.1.3.1-1.5.noarch
I’ve been using LibreOffice & it’s ancestors right back to StarOffice & never had this problem - I’m totally baffled.

[erAck]

Instead of adding that as an answer to the the question, which it is not, adding it as comment or just an edit to the original question would had been better. However… what UI language do you use, and if it is not en-US then it is missing from that list. And which distro are we talking about anyway…?