I have LibreOffice Verzion: 5.2.7.2 , ID build: 1:5.2.7-1+deb9u4 OS: Linux 4.9; in menu Export I have not choice for output in MS format… export is automaticlly to PNG format. Have I to take actualization?
Did you try it with File>Save as?
The same thing… not any choice for format saving…
And what is the source file format actually?