Version: 2.5.5721
When I create an external playlist (from within MusicBee) and save it in a folder it gets "invisible" after refreshing the folder tree (F5) and also after restarting MusicBee. It only shows up again after closing MusicBee, renaming the folder (in a file manager), and restarting MusicBee again but a restart after that (or refresh of the tree) will make it invisible again, etc.