I've had 2 things happen while I had a Deluxe AP and for some reason, was surprised when I tried to enter on a blocked day (2 separate trips).
One time they just let me go through, no extra charge. The other time I was charged $40. I have no idea why, but that's what happened and I started paying closer attention to the blocked days calendar.
Then I got a Premier Pass since we were going to WDW and DL within the same year. No blocked days.