Settings/System Settings/USB Mode. Change it to MTP, which is probably what you were using before.
Your firmware update must have switched the USB mode. Apparently you were using MTP before, and now you’re in MSC. Your computer can only see files that were sent over in the current mode, although your Fuze sees everything.
By the way, drag-and-drop won’t work on video, though that didn’t cause your problem. You have to put video through a converter to make it fit the Fuze screen. The Sansa Media Converter, available through the updater, makes many people unhappy, so try Video4Fuze. Download the .exe file on the right side of the page and install it.
