LibreOffice Writer 24.8.6.1 @win10 Double struck capital letter like: 𝔼 (U+1D53C), 𝕆 (U+1D546) ... Are not displayed within math formulas. Checked both for opensymbol TTF and cambria math. Jest empty space is displayed where the double struck capital should be.
Are you creating a new Symbol in the Symbol Catalog? Or just attempting to enter as a literal? If the later you will need to enclose in double quotes, and probably also make a Fonts.. assignment to the 'Text:' fonts, something with coverage of the SMP Unicode points. You can use an <Alt>+X conversion withing the quotes for the literal, or just paste if you've got a source. But creating your own entries in a Symbol set, assigning a glyph from a font with coverage, will be more efficient. The new symbol(s)/symbol set(s) will be written to user profile for reuse. The <F1> help for the Symbol... dialog https://help.libreoffice.org/25.8/en-US/text/smath/01/06010000.html https://help.libreoffice.org/25.8/en-US/text/smath/01/06010100.html Coverage in the Math Guide is a little dated as it does not yet cover the new Arabic math symbols and some of the additional font support. But still worth keeping handy. https://books.libreoffice.org/en/MG252/MG25200-Preface.html