Have you set a touring plans reservation finder (it’s free)? The only reason it didn’t work with the mass release is there are hundreds of people looking at that same time frame. You can keep resetting it if you don’t login fast enough. On top of that, do manual searches periodically when you have time. Definitely up your game 2 days before you go. I’ve seen many cancellations before the cutoff to avoid cancellation fees.
I don’t know anything about the walk up list, maybe someone else can answer.