I did a search and could not find an answer…
I set up some templates and had been manipulating them using the Portable Version of LibreOffice (6.3.X.X). The default font was/is Liberation Serif in all of my tremplates. I updated to the Portable Version of LibreOffice (6.4.0.3) and Liberation Serif is now saying that the font is NOT available. I stuck with the default to avoid this issue
The only thing I can think of is that I created the Templates with an installed version of LibreOffice on a machine that has since been donated. I tend to use Portable Apps now.
Update:
Confirmed, The default font in LibreOffice is Liberation Serif (https://caninfotech.com/office-suites/change-default-font-libreoffice/). The portable app NEEDS to be packaged with the correct fonts. Where do we make this request?