I have noticed this effect for some time. You can word wrap individual Pivot table cells or entire spreadsheet rows. You can do this via the format menu, the ribbon, or the properties window. Regardless of how you do it, a refresh resets to disable word wrap for the Pivot table cells (but not the cells outside the Pivot table – if you word wrapped entire spreadsheet rows). I could perhaps change the Styles, but this might create unintended consequences in other Pivot tables.
Right now I’m using LibreOffice Version 6.4.0.3, but I have noticed this effect as far back as Version 3.x – in both Windows and Linux editions. To the best of my memory, I have seen this effect on more than one of my laptops, so neither hardware nor OS seem to play a role.
Is this a bug, or am I missing something?
(search word “format” inserted into the subject by @Lupp)