Though I moved my library from my Windows PC to the new MBP even after correctly changing the file paths to reflect the Mac OS's naming conventions, AM would start the sync and finish in no time making the sync suspect. My assumption was AM would take care of the syncing as long as the library on the MBP was up-to-date with the right paths and the files. What finally solved the issue for me was to physically/deliberately/redundantly add the root folder containing my songs (not the default Music folder, but the one on a separate volume) to the library (File->Add to Library menu option). This did the trick and that's when I could see all my song's Artists/Albums/Genres and playlists show up in the list when I click the sync button.