Are you trying to do it via the app, @Chris13939 ? I tried to do that over and over (likely a dozen times) last night on the app -- saved, and saved, and saved, and was getting frantic. I REALLY needed those dates blocked.
By the time I got home to my laptop to try from there, my block was finally showing up, even though it had refused to show as saved on the app. By that time it was showing as blocked on the app as well.