I checked 9 nights for all of your desired arrival dates & there is currently no availability for that. I tried a few one-nights within your range and also found one. It's not a glitch, though, as I found availability later in the month. Here are the 9-night availabilities I found at Wilderness Lodge in December:
12/15 - 12/24 nature fireworks view (sleeps 4) and nature fireworks view king bed (sleeps 2)
12/22 - 12/31 nature fireworks view (sleeps 4) and stanard view king bed (sleeps 2)
12/26 - 1/4 nature fireworks view (sleeps 4)
Early December has become an extremely popular time to visit Disney World (the decorations are up, and people think it will be less busy than Christmas week), and WL is one of the most popular resorts around Christmas because it's style is naturally suited to the holiday. In addition, a lot of WL rooms were converted into DVC Copper Creek studios a fews years back, so there are less WL rooms than there are rooms at most resorts. And DVC owners love to book in the fall, so you're unlikely to find availability there, either.