Do you encounter the following pb with C6.0.1 ?
1/ make a mix
2/ Export mix in Mp3 => OK
3/ modify the mix
4/ Export mix again, Cubase says the mp3 already exist and propses to replace it
5/ Clic on “replace” => KO, nothing is done, you go back immediatly to the export popup and the first mp3 mix has not been replaced by the second one.
6/ I’m obliged to export the mix with another filename.