AFAIK, most backup products do not have a feature whereby you can request that pre-emptive walk of a file system be run to identify files that are going to be missed by future backups. Instead, do what any of us would do, which is to look for status 1 backups. These are partial backups. Once you have the server names then you can logon to inspect the servers.
The activity monitor job log will list some of the skipped folders/files, but if the backup client doesn't even have the permission to enter the folder, then you'll never see the file names of missed files.