For some reason dll files (and possibly others) are greyed out and could not be restored during FLR.
Suggested workaround is to restore a parent folder with all files inside. This could be a time consuming task with large directories like System32.
There is another approach to this issue. As we know, during FLR Windows Guest disks are mounted to some temp directory under current user. We can browse to this location and pickup all necessary files.
'Side' effect to this approach is that searching mount point can be a viable alternative to the Catalog feature.
Catalog can be annoying, hard to install and manage feature requiring a separate local database. I'd rather delegate this feature (finding files) to standard Windows tools.
Yes, it is slower to search for files on the disk than get immediate location from the indexed DB. But how often do you restore files and do not know their location?
Another drawback is that Windows search won't locate files in multiple savepoints as Catalog does. Basically you need to launch FLR against some savepoint to be able to look for the files.