I often encounter a bug where I can't save my project (the save option is grayed out, Cubase 13)

The save shortcut key and save option are invalid.
Every time I encounter this bug, I can only restart Cubase13 to restore it to normal.
This problem makes me lose the project I just completed, which makes me very frustrated!

It looks like Save As… is still available (based on the shortcuts, can’t read it) which would at least keep you from loosing work.

The only thought I’ve got is that the destination media might be offline or otherwise unavailable. Anything unusual about where the Project is saved?

Thanks for your help!
Yes, the Save As option is still available. I can only use the Save As option to save the file and overwrite the original project file.
Regarding the original project file, I can confirm that it is not offline, because it is saved in the system disk of the Mac. If there is a problem with the system disk, my Mac will not work properly.
On the other hand, I have confirmed the existence of the project file and it has not been tampered with or deleted.
In fact, when I restart Cubase and open the project again, the save function will resume normal operation, so I think it can be ruled out that there is something wrong with the project file.