LO 18.104.22.168 is running on macOS. I created a spreadsheet with just one line of text using a TTF font. I ticked the box to embed the font (File->Properties->Font->Embed fonts in the document).
I transferred the file to an Ubuntu machine running LO 22.214.171.124. The font was not displayed. I checked the document properties and the box was still ticked (Embed fonts in the document), so the setting was correctly preserved but the font was not displayed.
Is this a bug and if so, is there a workaround?