After restart and re-enabling Plex on My Cloud Home, no files shown in libraries

Hi smart people,

I disabled Plex on My Cloud Home, deleted all folders (including Plex), restarted My Cloud Home, enabled and configured Plex (Plex folder, including all (shared) subfolders, i.e. Shared Movies got created), and I am able to connect to My Cloud Home Duo using Plex web interface. I also added one movie to Shared Movies folder…

However, when I go to Plex web interface Manage->Libraries, only Movies, TV Shows, Music, Photos, and Other Videos libraries are shown, and there are no Shared subfolders (visible in, nor their content in any Manage->Libraries, even after re-scanning manually all of them.

What could be the issue? This is extreemly unintuitive, even for IT pro.