In Nuendo the red text in the Pool usually indicates that something about the file status is not normal. Most commonly it means the files are missing, offline, or not currently found in the expected location.
It can also happen if the media was moved outside the project folder or if the project was opened before the drives containing the audio were mounted.
You might want to try “Find Missing Files” or “Prepare Archive” from the Pool menu and see if Nuendo reports anything. Sometimes simply relinking the files or refreshing the Pool resolves it.
I was opening the Project directly from the backup drive to check something for the client just visually, after I deleted the original data from the audio SSDs already. Obviously, that’s something I don’t do regularly.