If you share a sub-folder to a folder (or drive) that is already shared any media will not appear. Its not an easy thing to explain so bear with me, but to try to understand why this occurs lets use an example where you are sharing your D:\ root folder and the D:\abc\def subfolder - when Serviio scans for media to add to your library it:
- Scans for media in your first shared folder: ie scans your D:\ folder and all its subfolders. Eventually it will scan to subfolder D:\abc\def and find your media file (eg. video.mkv). It adds this file to its library database, storing the full filename (ie. D:\abc\def\video.mkv) against the D:\ folder repository in the database.
- After scanning your first shared folder it moves on to the next shared folder: ie. it scans your D:\abc\def folder and all its subfolders. Eventually it will come to your video.mkv file and attempt to store it in the library database - the first thing it does is see if that file already exists in the library. As this file name (ie. D:\abc\def\video.mkv) has already been added to the library by the first shared folder scan, Serviio skips adding a record in the database against the D:\abc\def repository. Hence when you view the repository that represents the shared folder D:\abc\def it appears empty.
Hope this makes sense.
You could try changing the order of your shared folders so that the sub-folder appears first - this will reverse the issue: media.mkv will appear in the shared sub-folder but not if you navigate through from the root folder. I've never tested this so if you do proceed, let us know if it works (it should).