Only commenting here to say that I have also found that Cubase fails to replace the audio in my videos. The videos load fine and the audio is extracted fine but replacement hasn’t worked for years, since the old SX version I reckon.
I’ve got no quick solution I’m afraid. Most recently I simply had to load up an old version of Premiere on an old PC and re-render it all. The problem with that of course is that the video is decompressed and then recompressed at some ‘guess’ settings because I’m no video expert!
I wish there was some updating in this part of the application.
Mike.