Cubase not locking audio files when open

I don’t know if this is a problem or normal behaviour so I would like some feedback before I make an issue of it.

I have been under the impression that when Cubase was open, all audio in the Pool would be locked so you couldn’t delete those files from the OS.

That is exactly what I have just managed to do, but not all, just some. The files that I couldn’t delete from the OS had all been VariAudioed. That seems to be the only difference but I have attached a screengrab of the Pool, Audio folder and Recycle Bin just to shown how similar everything seems to be. Apart from the VA, of course.

This inconsistency seems slightly illogical. I can see why you would want to lock a file when the project is holding VA or Warp data on it, but why - for the sake of safety if nothing else - wouldn’t you lock any file that the project depended on?

On a slightly broader point, I’ve had locking problems in other situations, where for some reason I have been unable to rename a file. Difficult to reproduce at will, but I’m wondering if there’s a locking issue lurking about. See this thread for more:
Deleted and undeleted files from Pool.JPG