Example using Chrome & Adding the album Abbey Road:
On the Media Player screen, in Moose, click on the Gear icon on top of the right side column ( just below the search entry field ). In this Settings screen scroll down to "Show missing files and folders from MPD database". Check the box. Now any new folder(s) or file(s) you add to your library will show in red, along with other hidden files such as album art.
These red files are at the bottom of the list of folder(s) or file(s) you are looking at, so if your looking for The Beatles / Abbey Road folder that you just added, it will be on the bottom of the list of albums where Abbey Road is supposed to be, but not at B as you would expect. Once you have scrolled down to the bottom to find Abbey Road Click on the + sign on the Abbey Road listing and it will be Updated to the library.
Update on the top left will turn blue for a very short time then back to white, but the album listing for Abbey Road will remain red until you back out and go back into the album list at which point it will show in gray and be in the proper alphabetical location.