That is a known Microsoft OneDrive problem. The solution is in the link below:
Latest version of Audirvana Studio can’t see local files - Studio / Local library - Audirvana
Quote from the link:
Thanks for the reply. OneDrive was indeed the problem. On investigation I noticed that the Desktop folder Audirvana was seeing was the synced folder on OneDrive - I think this must have set when I reinstalled Windows. Looks like this has caused multiple problems. This fix on the MS website worked and I’m now able to sync all my local folders. Thanks again for your help it’s, good to know there many happy Windows users