OOPS. Typed this last night but didn't hit SEND. Thanks to RunCat and Shankilicious for filling in my knowledge holes.
So it could be that if you're EOY, you'll do better by booking through Owner's Services.
Right now, the following appears on the Owner sign-in screen: "PLATINUM PRIORITY PROGRAM OWNERS - While we work on enhancing your online experience, your previous “Platinum Rewards Program” benefits and extended booking windows are still in place. If you qualify for an additional booking window—and would like to take advantage of it—please call Owner Services." Quite frankly, I can't figure out what's going on. I'll see a week I want to book, and then it disappears when I search again. Then when I call Owner Services, it turns out to be available. I think they have a few bugs in the system.
In other words, if you can't find what you want online, don't give up without calling Owner Services. In fact, I recently mentioned that "I almost gave up," and the Welk rep said, "Oh, never give up. You should always try calling us!"