Update: I just played and got the 6-day experience. I think maybe I got the 5-day during the first blitz game I played yesterday when the experience page showed blank, but I didn't know I got it. So the rest of the day I was waiting to see it, but I must have it already.
I guess the only thing left is why the experience page displayed blank after two blitz games (I clicked on the "Blitz game objective" and created a 2-player blitz game with the default settings, so I would get the objective experience for both games. Hope that helps.