A well used calc spread sheet after opened in Version 3.6.5.2 for the 1st time has had all relative references converted from relative to absolute.
i.e.
=IF('Basic Track Data'!$A5=0,"",'Basic Track Data'!$F6)
has become
=IF('Basic Track Data'!$A$5=0,"",'Basic Track Data'!$F$6)
and
=IF(ISBLANK($A$4),"",LOWER(ROMAN(IF(ISBLANK($A$4),0,$A$4),4)))
has become
=IF(ISBLANK($A4),"",LOWER(ROMAN(IF(ISBLANK($A4),0,$A4),4)))
This can create problems since the calc will produce the same results until a formula with relative references is edited i.e. by adding rows or columns, etc.
I suspect this is a bug but Bugzilla is down.
Update: Bug filed https://bugs.freedesktop.org/show_bug.cgi?id=60756