Oh wow, I was just about to post a question about this. I’m relatively new to Cubase, starting with v13. The whole audio folder thing and the fact you have to use Backup Project just to move it is quite odd to me (why not just let users in media pool select a new folder?).
But anyway, I’ve been frustrated lately when I work on a new idea and record some audio, then I would like to use the Backup Project function to redirect everything to a properly named project folder, but I have noticed it is grayed out too, until you save it first. Then you can back it up but you have the extra steps of having to go delete the saved project. Although I’m pretty new I don’t think I remember that being the case in v13.
According to this thread I found from last year, it seems the workflow you describe is common! Hopefully the devs can restore this behavior (and while we’re at it, please let us redirect the audio folder without having to use backup project!)