Server Version#:4.160.0
Player Version#:n/a
This is on server-linux;
When creating new library (possibly when editing them as well) if you add a path, then another path, so you have to paths, go on until the end of the wizard, then go back to remove on of the paths you added, at the end the library will be added with the 2 paths anyways ( you can see it in the summary); summary says 1 path + 1 (so 2 paths), yet the path selector only shows 1 path (the one you left alone, the other you deleted)
This is unexpected.
tldr once you add a path it can never be deleted. In my case these were smb shares but I think this would do the same with plain directories on the local filesystem.