I have the same problem. I don’t understand what you are saying. I just drag to the sync section of the Media Player. Then Media Player says the files are on the device, but they don’t show up on the Sansa Fuse music list when I disconnect the Sansa Fuse. Are these folders you are talking about in Media Player? How does that help me find the songs on the device’s music list?
You are entering the folder navigation (aka. folder view) on the Fuze by:
turning the Fuze on or disconnecting the player from the computer if you were just copying files
select Music from the main menu
scroll down to the last item called Folders
right-click on Folders
If you have attached a microSD card, you have to choose between internal and external storage. Otherwise you are directly presented with all the folders of your device which contain music files. Note, that if your files were transfered from PC using MTP connection mode the relevant folders MUSIC, AUDIOBOOKS etc. are located below the item MTP and file names may have changed (due to the nature of the MTP protocol).
Now you should check if you can find all your files. By folder navigation it is done regardless of any - possibly erroneous - tag information. The two different operating modes tag-based browsing via genre, album etc. and folder navigation by locating file names allow you to narrow down your problems. If the “missing tracks” are actually on the device but don’t show up during usual tag-based browsing than there can be different reasons:
Hope that helps in the first step.