Hi,
Did you set the font color with the Fill.Color property?
TMSFMXHTMLText1.Fill.Color := gcRed;
TMSFMXHTMLText1.Text := '<B>Test</B>';
TMSFMXHTMLText1.Text := '<B>Test</B>' + #13#10 + 'new line';
TMSFMXHTMLText1.Text := '<B>Test</B>' + #13#10 + 'new line';
This works as expected here.